Operation can refer to medical surgery, a military campaign, or mathematical methods, such as multiplication and division.

Operation comes from the Latin word opus (“work”) and can refer to a whole range of practical activities and work. In driver's education, you learn the proper operation of a motor vehicle. If you’re going to make your lemonade franchise a success, you’re going to have to learn the rules for prudent operation of a business — how to run it — and you’ll also have to figure out the operation of a lemon squeezer.

Definitions of operation
  1. noun
    process or manner of functioning or operating
    “the power of its engine determines its operation
    “the plane's operation in high winds”
    synonyms: functioning, performance
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    type of:
    physical process, process
    a sustained phenomenon or one marked by gradual changes through a series of states
  2. noun
    a process or series of acts especially of a practical or mechanical nature involved in a particular form of work
    “the operations in building a house”
    “certain machine tool operations
    synonyms: procedure
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    type of:
    activity directed toward making or doing something
  3. noun
    the activity of operating something (a machine or business etc.)
    “her smooth operation of the vehicle gave us a surprisingly comfortable ride”
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    type of:
    any specific behavior
  4. noun
    the state of being in effect or being operative
    “that rule is no longer in operation
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    the state of being in good working order and ready for operation
    the state of being in operation
    the state of an engine or other mechanism that is idling
    type of:
    action, activeness, activity
    the state of being active
  5. noun
    a business especially one run on a large scale
    “a large-scale farming operation
    “a multinational operation
    “they paid taxes on every stage of the operation
    “they had to consolidate their operations
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    type of:
    business activity, commercial activity
    activity undertaken as part of a commercial enterprise
  6. noun
    a planned activity involving many people performing various actions
    “they organized a rescue operation
    “the biggest police operation in French history”
    “running a restaurant is quite an operation
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    rescue operation
    an operation organized to free from danger or confinement
    undercover operation
    an operation involving secret work within a community or institution
    buy-and-bust operation
    an undercover operation by narcotics detectives to catch unsuspecting drug dealers
    type of:
    any specific behavior
  7. noun
    activity by a military or naval force (as a maneuver or campaign)
    “it was a joint operation of the navy and air force”
    synonyms: military operation
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    Meuse-Argonne operation
    an American operation in World War I (1918); American troops under Pershing drove back the German armies which were saved only by the armistice on November 11
    Operation Desert Storm
    the United States and its allies defeated Iraq in a ground war that lasted 100 hours (1991)
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    combined operation
    a military operation carried out cooperatively by two or more allied nations or a military operation carried out by coordination of sea, land, and air forces
    maneuver, manoeuvre, simulated military operation
    a military training exercise
    campaign, military campaign
    several related operations aimed at achieving a particular goal (usually within geographical and temporal constraints)
    naval campaign
    an operation conducted primarily by naval forces in order to gain or extend or maintain control of the sea
    military mission, mission
    an operation that is assigned by a higher headquarters
    reenforcement, reinforcement, support
    a military operation (often involving new supplies of men and materiel) to strengthen a military force or aid in the performance of its mission
    attack, onrush, onset, onslaught
    (military) an offensive against an enemy (using weapons)
    offence, offense, offensive
    the action of attacking an enemy
    peacekeeping, peacekeeping mission, peacekeeping operation
    the activity of keeping the peace by military forces (especially when international military forces enforce a truce between hostile groups or nations)
    amphibious operation
    a military operation by both land and sea forces
    information gathering
    the act of collecting information
    psychological operation, psyop
    military actions designed to influence the perceptions and attitudes of individuals, groups, and foreign governments
    covert operation
    an intelligence operation so planned as to permit plausible denial by the sponsor
    expedition, hostile expedition, military expedition
    a military campaign designed to achieve a specific objective in a foreign country
    combat mission
    a mission to capture or defend something
    search mission
    a mission to discover something
    search and destroy mission
    an operation developed for United States troops in Vietnam; troops would move through a designated area destroying troops as they found them
    close support
    close-in firing by one unit against an enemy engaged by another unit
    direct support
    a mission requiring one force to support another specific force and authorizing it to answer directly the supported force's request for assistance
    amphibious demonstration
    an amphibious operation conducted for the purpose of deceiving the enemy and leading him into a course of action unfavorable to him
    ground attack
    an attack by ground troops
    an impetuous rush toward someone or something
    banzai attack, banzai charge
    a mass attack of troops without concern for casualties; originated by Japanese who accompanied it with yells of `banzai'
    diversion, diversionary attack
    an attack calculated to draw enemy defense away from the point of the principal attack
    incursion, penetration
    an attack that penetrates into enemy territory
    blitz, blitzkrieg
    a swift and violent military offensive with intensive aerial bombardment
    an attack that is intended to seize or inflict damage on or destroy an objective
    counterattack, countermove
    an attack by a defending force against an attacking enemy force in order to regain lost ground or cut off enemy advance units etc.
    bombardment, bombing
    an attack by dropping bombs
    a large scale offensive (more than a counterattack) undertaken by a defending force to seize the initiative from an attacking force
    dirty war
    an offensive conducted by secret police or the military of a regime against revolutionary and terrorist insurgents and marked by the use of kidnapping and torture and murder with civilians often being the victims
    push back, rollback
    the act of forcing the enemy to withdraw
    amphibious assault
    an amphibious operation attacking a land base that is carried out by troops that are landed by naval ships
    intelligence, intelligence activity, intelligence operation
    the operation of gathering information about an enemy
    black operation
    a covert operation not attributable to the organization carrying it out
    fire, firing
    the act of firing weapons or artillery at an enemy
    an attack of machine-gun fire or cannon fire from a low flying airplane
    coup de main, surprise attack
    an attack without warning
    type of:
    any specific behavior
  8. noun
    (mathematics) calculation by mathematical methods
    “they were learning the basic operations of arithmetic”
    synonyms: mathematical operation, mathematical process
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    the act of changing the arrangement of a given number of elements
    the act of arranging elements into specified groups without regard to order
    the mathematical process of obtaining the derivative of a function
    maximisation, maximization
    the mathematical process of finding the maximum value of a function
    an operation used in the calculus whereby the integral of a function is determined
    exponentiation, involution
    the process of raising a quantity to some assigned power
    arithmetic operation
    a mathematical operation involving numbers
    matrix operation
    a mathematical operation involving matrices
    drawing a figure satisfying certain conditions as part of solving a problem or proving a theorem
    relaxation, relaxation method
    a method of solving simultaneous equations by guessing a solution and then reducing the errors that result by successive approximations until all the errors are less than some specified amount
    an arithmetic operation that is the inverse of multiplication; the quotient of two numbers is computed
    multiplication, times
    an arithmetic operation that is the inverse of division; the product of two numbers is computed
    minus, subtraction
    an arithmetic operation in which the difference between two numbers is calculated
    addition, plus, summation
    the arithmetic operation of summing; calculating the sum of two or more numbers
    matrix addition
    the addition of matrices
    matrix multiplication
    the multiplication of matrices
    matrix inversion
    determination of a matrix that when multiplied by the given matrix will yield a unit matrix
    matrix transposition
    the interchange of each row of a square matrix with the corresponding column
    the construction of a square having the same area as some other figure
    type of:
    calculation, computation, computing
    the procedure of calculating; determining something by mathematical or logical methods
  9. noun
    (computer science) data processing in which the result is completely specified by a rule (especially the processing that results from a single instruction)
    “it can perform millions of operations per second”
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    access, memory access
    (computer science) the operation of reading or writing stored information
    asynchronous operation
    operations that occur without a regular or predictable time relation to other events
    auxiliary operation, off-line operation
    a operation performed by off-line equipment not under the control of the central processing unit
    binary arithmetic operation, binary operation, boolean operation
    an operation that follows the rules of Boolean algebra; each operand and the result take one of two values
    computer operation, machine operation
    an elementary operation that a computer is designed and built to perform
    concurrent operation
    two or more operations performed at the same time (or within a give interval)
    control function, control operation
    an operation that controls the recording or processing or transmission of interpretation of data
    dyadic operation
    an operation on exactly two operands
    fixed-cycle operation
    an operation that is completed in a specified number of regularly timed execution cycles
    logic operation, logical operation
    an operation that follows the rules of symbolic logic
    monadic operation, unary operation
    an operation with exactly one operand
    multiplex operation
    an operation in which two or more activities are interleaved
    parallel operation, simultaneous operation
    the simultaneous execution of two or more operations
    printing operation
    an operation that controls the printing or display of information
    lookup, search
    an operation that determines whether one or more of a set of items has a specified property
    consecutive operation, sequential operation, serial operation
    the sequential execution of operations one after another
    sort, sorting
    an operation that segregates items into groups according to a specified criterion
    synchronous operation
    operations that are initiated predictably by a clock
    threshold operation
    an operation performed on operands in order to obtain the value of a threshold function
    disk access
    memory access to the computer disk on which information is stored
    carriage return
    the operation that prepares for the next character to be printed or displayed as the first character on a line
    floating-point operation, flop
    an arithmetic operation performed on floating-point numbers
    line feed
    the operation that prepares for the next character to be printed or displayed on the next line
    majority operation
    a threshold operation in which each operand is 0 or 1; output is 1 if and only if more than half the operands have the value 1
    new line
    the operation that prepares for the next character to be printed or displayed as the first character on the next line
    (computer science) the operation of accessing information from the computer's memory
    (computer science) the process of storing information in a computer memory or on a magnetic tape or disk
    type of:
    data processing
    (computer science) a series of operations on data by a computer in order to retrieve or transform or classify information
  10. noun
    (psychology) the performance of some composite cognitive activity; an operation that affects mental contents
    synonyms: cognitive operation, cognitive process, mental process, process
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    basic cognitive process
    cognitive processes involved in obtaining and storing knowledge
    higher cognitive process
    cognitive processes that presuppose the availability of knowledge and put it to use
    attending, attention
    the process whereby a person concentrates on some features of the environment to the (relative) exclusion of others
    lack of attention
    instinctive knowing (without the use of rational processes)
    the process of perceiving
    the process whereby perceived qualities of an object are related to past experience
    the cognitive process that leads to convictions
    categorisation, categorization, classification, sorting
    the basic cognitive process of arranging into classes or categories
    discrimination, secernment
    the cognitive process whereby two or more stimuli are distinguished
    acquisition, learning
    the cognitive process of acquiring skill or knowledge
    memory, remembering
    the cognitive processes whereby past experience is remembered
    representational process
    any basic cognitive process in which some entity comes to stand for or represent something else
    the examination of alternative hypotheses
    cerebration, intellection, mentation, thinking, thought, thought process
    the process of using your mind to consider something carefully
    the sequential mental process in which one thought leads to another by association
    deciding, decision making
    the cognitive process of reaching a decision
    a clear and certain mental apprehension
    language, linguistic process
    the cognitive processes involved in producing and understanding linguistic communication
    type of:
    cognition, knowledge, noesis
    the psychological result of perception and learning and reasoning
  11. noun
    a medical procedure involving an incision with instruments; performed to repair damage or arrest disease in a living body
    “they will schedule the operation as soon as an operating room is available”
    synonyms: surgery, surgical operation, surgical procedure, surgical process
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    catheterisation, catheterization
    the operation of introducing a catheter into the body
    ablation, cutting out, excision, extirpation
    surgical removal of a body part or tissue
    a surgical removal of all or part of a limb
    an operation to repair a damaged blood vessel or unblock a coronary artery
    surgical reconstruction or replacement of a malformed or degenerated joint
    a minimally invasive operation to repair a damaged joint; the surgeon examines the joint with an arthroscope while making repairs through a small incision
    brain surgery
    any surgical procedure involving the brain
    surgical removal of the testes or ovaries (usually to inhibit hormone secretion in cases of breast cancer in women or prostate cancer in men)
    cauterisation, cauterization, cautery
    the act of coagulating blood and destroying tissue with a hot iron or caustic agent or by freezing
    use of chemical to destroy diseased or malignant tissue; used in treatment of skin cancer
    a surgical opening through the skull
    the use of extreme cold (usually liquid nitrogen) to destroy unwanted tissue (warts or cataracts or skin cancers)
    curettage, curettement
    surgery to remove tissue or growths from a bodily cavity (as the uterus) by scraping with a curette
    surgical removal of foreign material and dead tissue from a wound in order to prevent infection and promote healing
    removal of the outer covering of an organ or part
    D and C, dilatation and curettage, dilation and curettage
    a surgical procedure usually performed under local anesthesia in which the cervix is dilated and the endometrial lining of the uterus is scraped with a curet; performed to obtain tissue samples or to stop prolonged bleeding or to remove small tumors or to remove fragments of placenta after childbirth or as a method of abortion
    surgery performed with electrical devices (as in electrocautery)
    enterostomy, enterotomy
    surgical operation that creates a permanent opening through the abdominal wall into the intestine
    surgical removal of something without cutting into it
    wrong-site surgery
    a surgical operation performed on the wrong part of the body
    surgical removal of an organ (or the contents of an organ) from a patient
    surgical removal of the organs within a body cavity (as those of the pelvis)
    eye operation, eye surgery
    any surgical procedure involving the eyes
    surgical procedure that creates a new fenestra to the cochlea in order to restore hearing lost because of osteosclerosis
    surgical removal of all or part of the stomach
    surgical creation of an opening between the stomach wall and the small intestines; performed when the normal opening has been eliminated
    surgical creation of an opening through the abdominal wall into the stomach (as for gastrogavage)
    heart surgery
    any surgical procedure involving the heart
    haemorrhoidectomy, hemorrhoidectomy
    surgical procedure for tying hemorrhoids and excising them
    surgical incision into the uterus (as in cesarean section)
    a surgical procedure that places something in the human body
    intestinal bypass
    surgical operation that shortens the small intestine; used in treating obesity
    surgical creation of an opening between the jejunum and the anterior abdominal wall; will allow artificial feeding
    major surgery
    any surgical procedure that involves anesthesia or respiratory assistance
    surgery using operating microscopes and miniaturized precision instruments to perform intricate procedures on very small structures
    minor surgery
    any surgical procedure that does not involve anesthesia or respiratory assistance
    surgical incision or division of a muscle
    surgical removal of the eardrum
    surgical repair of a perforated eardrum with a tissue graft
    surgical incision into the eardrum (to relieve pressure or release pus from the middle ear)
    any surgery that involves the nervous system (brain or spinal cord or peripheral nerves)
    operation to bring an undescended testicle into the scrotum
    surgical sectioning of bone
    surgical procedure that creates an artificial opening for the elimination of bodily wastes
    PPP, UPPP, palatopharyngoplasty, uvulopalatopharyngoplasty
    surgical resection of unnecessary palatal and oropharyngeal tissue to open the airway; intended to cure extreme cases of snoring (with or without sleep apnea)
    surgical removal or all or part of a vein; sometimes done in cases of severe varicose veins
    surgical procedure that uses an intense laser beam to destroy diseased retinal tissue or to make a scar that will hold the retina in cases of detached retina
    anaplasty, plastic surgery, reconstructive surgery
    surgery concerned with therapeutic or cosmetic reformation of tissue
    surgical removal of a polyp
    surgical removal of part of a structure or organ
    surgical procedure in which an incision is made in the nose to drain accumulated pus
    surgical procedure in which spinal nerve roots are cut; done (anterior roots) to relieve intractable pain or (posterior roots) to stop severe muscle spasms
    sex-change operation, transsexual surgery
    surgical procedures and hormonal treatments designed to alter a person's sexual characteristics so that the resemble those of the opposite sex
    Shirodkar's operation, purse-string operation
    a surgical procedure in which a suture is used to close the cervix in a pregnant woman; is performed when the cervix has failed to retain previous pregnancies
    sterilisation, sterilization
    the act of making an organism barren or infertile (unable to reproduce)
    the surgical operation of cutting a muscle or tendon of the eye in order to correct strabismus
    the surgical procedure of manually restoring a displaced body part
    tracheostomy, tracheotomy
    a surgical operation that creates an opening into the trachea with a tube inserted to provide a passage for air; performed when the pharynx is obstructed by edema or cancer or other causes
    organ transplant, transplant, transplantation
    an operation moving an organ from one organism (the donor) to another (the recipient)
    an operation that removes a circular section of bone from the skull
    surgical correction or repair of defects or injuries in the eardrum or the bones of the middle ear
    surgical correction of a defect of the palate
    a surgical procedure that attempts to restore the function of the vas deferens after a vasectomy
    the act of operating on living animals (especially in scientific research)
    abdominoplasty, tummy tuck
    cosmetic surgery of the abdomen to remove wrinkles and tighten the skin over the stomach
    surgical removal of the adenoids; commonly performed along with tonsillectomy
    adrenalectomy, suprarenalectomy
    surgical removal of one or both adrenal glands
    appendectomy, appendicectomy
    surgical removal of the vermiform appendix
    the surgical fixation of a joint which is intended to result in bone fusion
    surgical repair by using tissue from another part of the patient's own body
    brain surgery on human patients intended to relieve severe and otherwise intractable mental or behavioral problems
    split-brain technique
    brain surgery on animals in which the corpus callosum (and sometimes the optic chiasm) is severed so that communication between the cerebral hemispheres is interrupted
    a surgical operation that creates an opening from the colon to the surface of the body to function as an anus
    surgical removal of the gall bladder (usually for relief of gallstone pain)
    clitoridectomy, female circumcision
    excision of the clitoris
    suction curettage, vacuum aspiration
    a method of induced abortion; prior to the 14th week of gestation the embryo and placenta are removed by applying suction to the dilated cervix
    surgical removal of an embolus (usually from an artery)
    surgical removal of the inner lining of an artery that is clogged with atherosclerosis
    surgical removal of a nerve
    cosmetic surgery, face lift, face lifting, facelift, lift, nip and tuck, rhytidectomy, rhytidoplasty
    plastic surgery to remove wrinkles and other signs of aging from your face; an incision is made near the hair line and skin is pulled back and excess tissue is excised
    closed-heart surgery
    heart surgery in which a small incision is made (the chest cavity is not opened)
    open-heart surgery
    heart surgery in which the rib cage is spread open, the heart is stopped and blood is detoured through a heart-lung machine while a heart valve or coronary artery is surgically repaired
    surgical removal of the pituitary gland
    surgical removal of the uterus
    cataract surgery
    eye surgery that involves removing all or part of the lens and replacing it with an intraocular lens implant
    cyclodestructive surgery
    an eye operation that treats glaucoma by destroying the ciliary body with a laser
    filtration surgery
    eye surgery that opens a passage allowing excess aqueous humor to drain into surrounding tissues; a treatment for glaucoma
    an eye operation that treats closed-angle glaucoma by surgical removal of part of the iris of the eye
    a surgical procedure that makes an incision in the iris of the eye in order to enlarge the pupil or to treat closed-angle glaucoma
    surgical incision into the cornea
    LASEK, laser-assisted subepithelial keratomileusis
    a refractive surgery procedure that reshapes the cornea
    laser trabecular surgery
    eye surgery that makes many tiny laser burns in an area that will increase the drainage of aqueous humor
    LASIK, laser-assisted in situ keratomileusis
    a refractive surgery procedure that reshapes the cornea
    a surgical procedure that removes the vitreous humor and replace it with saline solution
    surgical procedure that creates an opening from the ileum through the abdominal wall to function as an anus; performed in cases of cancer of the colon or ulcerative colitis
    corneal graft, corneal transplant, keratoplasty
    a surgical procedure in which part or all of a damaged or diseased cornea is replaced by healthy corneal tissue from a donor
    lipectomy, selective lipectomy
    plastic surgery involving the breakdown and removal of fatty tissue
    plastic surgery to lift or reshape the breasts
    plastic surgery of the nerves
    reconstructive surgery of the auricle of the external ear
    surgical removal of the bony arches on one or more vertebrae
    surgical removal of part or all of the larynx (usually to treat cancer of the larynx)
    surgical removal of a stone (calculus)
    surgical removal of a lobe from any organ of the body (as the lung or brain)
    surgical removal of a tumor without removing much of the surrounding tissue or lymph nodes; performed in some cases of breast cancer
    robotic telesurgery
    microsurgery in which the surgeon performs surgery by manipulating the hands of a robot
    surgical removal of a breast to remove a malignant tumor
    surgical removal of some or all of the mastoid process
    surgical removal of the meniscus of the knee
    surgical removal of a kidney
    surgical removal of all or part of a nerve
    oophorectomy, ovariectomy
    surgical removal of one of both ovaries
    surgical removal of one or both ovaries and the corresponding Fallopian tubes
    surgical removal of an eye
    orchidectomy, orchiectomy
    surgical removal of one or both testicles
    surgical removal of part or all of the pancreas
    surgical removal of a lung (usually to treat lung cancer)
    surgical removal of part or all of the prostate gland
    surgical removal of one or both Fallopian tubes
    surgical removal of all or part of a septum (especially the nasal septum or atrial septum)
    surgical removal of part or all of the sigmoid colon (usually to remove a malignant tumor)
    surgical removal of the spleen
    surgical removal of the stapes of the middle ear
    surgical interruption of a nerve pathway in the sympathetic nervous system
    surgical removal of a blood clot (thrombus) from a blood vessel
    surgical removal of the thyroid gland
    surgical removal of the palatine tonsils; commonly performed along with adenoidectomy
    reconstructive surgery on the penis to repair congenital abnormality or injury
    proctoplasty, rectoplasty
    reconstructive surgery of the anus or rectum
    altering, fixing, neutering
    the sterilization of an animal
    TURP, transurethral resection of the prostate
    removal of significant amounts of prostate tissue (as in cases of benign prostatic hyperplasia)
    application of a substance that destroys tissue by freezing it
    cautery (destruction of tissue) by heat
    surgical procedure that removes all or part of the vas deferens (usually as a means of sterilization); is sometimes reversible
    surgical removal of part or all of the vulva
    surgical contraception
    contraception by surgical sterilization
    xenotransplant, xenotransplantation
    a surgical procedure in which tissue or whole organs are transfered from one species to another species
    type of:
    medical procedure
    a procedure employed by medical or dental practitioners
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