A tube is a pipe shape, a cylinder with a hollow space inside. If you're like most people, you sip your milkshake through a straw — a long, plastic tube.

Chemists use glass tubes in labs, and plumbers work with pipes — tubes made of plastic and metal. Another kind of tube is the rubber one inside a tire. If you slide down a snowy hillside on an inflated tire tube, or ride through choppy water while sitting on one, you can also use tube as a verb. Though it's not true in the US, in London the subway is also familiarly known as the Tube.

Definitions of tube
  1. noun
    a hollow cylindrical shape
    synonyms: pipe
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    type of:
    a surface generated by rotating a parallel line around a fixed line
  2. noun
    conduit consisting of a long hollow object (usually cylindrical) used to hold and conduct objects or liquids or gases
    synonyms: tubing
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    trans-Alaska pipeline
    an oil pipeline that runs 800 miles from wells at Prudhoe Bay to the port of Valdez
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    barrel, gun barrel
    a tube through which a bullet travels when a gun is fired
    blow tube, blowgun, blowpipe, blowtube
    a tube through which darts can be shot by blowing
    blow tube, blowpipe, blowtube
    a tube that directs air or gas into a flame to concentrate heat
    a small flexible tube inserted into a body cavity for draining off fluid or introducing medication
    capillary, capillary tube, capillary tubing
    a tube of small internal diameter; holds liquid by capillary action
    a thin flexible tube inserted into the body to permit introduction or withdrawal of fluids or to keep the passageway open
    cigarette holder
    a tube that holds a cigarette while it is being smoked
    tubing that is wound in a spiral
    chromatography column, column
    a vertical glass tube used in column chromatography; a mixture is poured in the top and washed through a stationary substance where components of the mixture are adsorbed selectively to form colored bands
    tube inserted into a body cavity (as during surgery) to remove unwanted material
    hose, hosepipe
    a flexible pipe for conveying a liquid or gas
    inner tube
    an inflatable rubber tube that fits inside the casing of a pneumatic tire
    the tube of a pipe or cigarette holder that a smoker holds in the mouth
    pea shooter
    a straight narrow tube through which pellets (as dried peas) can be blown at a target
    pipage, pipe, piping
    a long tube made of metal or plastic that is used to carry water or oil or gas etc.
    pipe, tobacco pipe
    a tube with a small bowl at one end; used for smoking tobacco
    short tube attached to the muzzle of a gun that deadens the sound of firing
    siphon, syphon
    a tube running from the liquid in a vessel to a lower level outside the vessel so that atmospheric pressure forces the liquid through the tube
    speaking tube
    a tube for conveying the sound of a voice from one room to another
    the tube of a tobacco pipe
    a slender tube inserted inside a tubular body part (as a blood vessel) to provide support during and after surgical anastomosis
    drinking straw, straw
    a thin paper or plastic tube used to suck liquids into the mouth
    test tube
    glass tube closed at one end
    torpedo tube
    a tube near the waterline of a vessel through which a torpedo is fired
    a tube with a constriction; used to control fluid flow (as in the air inlet of a carburetor)
    well point, wellpoint
    a perforated tube driven into the ground to collect water from the surrounding area
    air hose, airline
    a hose that carries air under pressure
    briar, briar pipe
    a pipe made from the root (briarroot) of the tree heath
    calabash, calabash pipe
    a pipe for smoking; has a curved stem and a large bowl made from a calabash gourd
    calumet, peace pipe, pipe of peace
    a highly decorated ceremonial pipe of Amerindians; smoked on ceremonial occasions (especially as a token of peace)
    a short earthenware pipe on the top of a chimney to increase the draft
    clay pipe
    a pipe made of clay
    a hollow coil that condenses by abstracting heat
    discharge pipe
    a pipe through which fluids can be discharged
    drain, drainpipe, waste pipe
    a pipe through which liquid is carried away
    drilling pipe
    a series of tubes (joined by screwed collars) that connect a drilling platform to the drilling bit; rotates the bit and supplies drilling mud
    a length of pipe with a sharp bend in it
    endotracheal tube
    a catheter that is inserted into the trachea through the mouth or nose in order to maintain an open air passage or to deliver oxygen or to permit the suctioning of mucus or to prevent aspiration of the stomach contents
    exhaust pipe
    a pipe through which burned gases travel from the exhaust manifold to the muffler
    fire hose
    a large hose that carries water from a fire hydrant to the site of the fire
    fuel line, gas line, petrol line
    a pipe that carries gasoline from a tank to a gasoline engine
    garden hose
    a hose used for watering a lawn or garden
    calean, chicha, hookah, hubble-bubble, hubbly-bubbly, kalian, narghile, nargileh, sheesha, shisha, water pipe
    an oriental tobacco pipe with a long flexible tube connected to a container where the smoke is cooled by passing through water
    a principal pipe in a system that distributes water or gas or electricity or that collects sewage
    a pipe that has several lateral outlets to or from other pipes
    a pipe having a bowl made of meerschaum
    line, pipeline
    a pipe used to transport liquids or gases
    radiator hose
    a flexible hose between the radiator and the engine block
    riser, riser main, riser pipe, riser pipeline
    a vertical pipe in a building
    sparge pipe
    a horizontal pipe having fine holes drilled throughout its length so as to deliver a spray of water
    a vertical pipe
    steam line, steam pipe
    a pipe conducting steam
    a pipe carrying fumes from the muffler to the rear of a car
    water cannon, watercannon
    a hose (carried on a truck) that fires water under high pressure to disperse crowds (especially crowds of rioters)
    type of:
    a passage (a pipe or tunnel) through which water or electric wires can pass
  3. noun
    (anatomy) any hollow cylindrical body structure
    synonyms: tube-shaped structure
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    a small tube
    a tube in the uterus or the ear
    the snail-shaped tube (in the inner ear coiled around the modiolus) where sound vibrations are converted into nerve impulses by the organ of Corti
    vas, vessel
    a tube in which a body fluid circulates
    a microscopically small tubule
    nephron, uriniferous tubule
    any of the small tubules that are the excretory units of the vertebrate kidney
    uveoscleral pathway
    a tubule that drains excess aqueous humor
    Eustachian tube, auditory tube
    either of the paired tubes connecting the middle ears to the nasopharynx; equalizes air pressure on the two sides of the eardrum
    blood vessel
    a vessel in which blood circulates
    Fallopian tube, oviduct, uterine tube
    either of a pair of tubes conducting the egg from the ovary to the uterus
    seminiferous tubule
    any of the numerous long convoluted tubules in the testis which are the sites where spermatozoa mature
    vasa efferentia
    the several highly convoluted tubules that lead from the rete testis to the vas deferens and form the head of the epididymis
    one of the tubules forming the respiratory system of most insects and many arachnids
    type of:
    anatomical structure, bodily structure, body structure, complex body part, structure
    a particular complex anatomical part of a living thing
  4. verb
    provide with a tube or insert a tube into
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    type of:
    furnish, provide, render, supply
    give something useful or necessary to
  5. verb
    convey in a tube
    “inside Paris, they used to tube mail”
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    type of:
    bring, convey, take
    take something or somebody with oneself somewhere
  6. verb
    place or enclose in a tube
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    type of:
    enclose, enfold, envelop, enwrap, wrap
    enclose or enfold completely with or as if with a covering
  7. verb
    ride or float on an inflated tube
    “We tubed down the river on a hot summer day”
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    type of:
    be carried or travel on or in a vehicle
  8. noun
    electronic device consisting of a system of electrodes arranged in an evacuated glass or metal envelope
    synonyms: electron tube, thermionic tube, thermionic vacuum tube, thermionic valve, vacuum tube
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    acorn tube
    a small vacuum tube; used at high frequencies
    diode, rectifying tube, rectifying valve
    a thermionic tube having two electrodes; used as a rectifier
    electron multiplier
    a vacuum tube that amplifies a flow of electrons
    gas-discharge tube
    a tube in which an electric discharge takes place through a gas
    an electron tube used to generate or amplify electromagnetic radiation in the microwave region by velocity modulation
    a diode vacuum tube in which the flow of electrons from a central cathode to a cylindrical anode is controlled by crossed magnetic and electric fields; used mainly in microwave oscillators
    a thermionic tube having five electrodes
    television pickup tube, television-camera tube
    a tube that rapidly scans an optical image and converts it into electronic signals
    a thermionic tube having four electrodes
    a thermionic vacuum tube having three electrodes; fluctuations of the charge on the grid control the flow from cathode to anode which makes amplification possible
    X-ray tube
    a vacuum tube containing a metal target onto which a beam of electrons is directed at high energy for the generation of X rays
    CRT, cathode-ray tube
    a vacuum tube in which a hot cathode emits a beam of electrons that pass through a high voltage anode and are focused or deflected before hitting a phosphorescent screen
    glow lamp
    a gas-discharge tube with a hot cathode; used in stroboscopes
    glow tube
    a gas-discharge tube consisting of a cold cathode and a diode in a tube filled with gas; the color of the glow depends on the particular gas
    the first practical television-camera for picture pickup; invented in 1923 by Vladimir Kosma Zworykin
    image orthicon, orthicon
    a now obsolete picture pickup tube in a television camera; electrons emitted from a photoemissive surface in proportion to the intensity of the incident light are focused onto the target causing secondary emission of electrons
    type of:
    electronic device
    a device that accomplishes its purpose electronically
  9. noun
    an electric railway operating below the surface of the ground (usually in a city)
    synonyms: metro, subway, subway system, underground
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    type of:
    railroad, railroad line, railway, railway line, railway system
    line that is the commercial organization responsible for operating a system of transportation for trains that pull passengers or freight
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