A principle is a kind of rule, belief, or idea that guides you. You can also say a good, ethical person has a lot of principles.

In general, a principle is some kind of basic truth that helps you with your life. "Be fair" is a principle that guides (or should guide) most people and businesses. A politician who tries to do the right thing rather than win votes is acting on principle. A person who has principles is a good, decent person. On the other hand, if you say someone has no principles, that means they're dishonest, corrupt, or evil.

Definitions of principle
  1. noun
    a basic generalization that is accepted as true and that can be used as a basis for reasoning or conduct
    “their principles of composition characterized all their works”
    synonyms: rule, tenet
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    a fundamental principle or practice
    the bright positive masculine principle in Chinese dualistic cosmology
    the dark, negative feminine principle in Chinese dualistic cosmology
    feng shui
    rules in Chinese philosophy that govern spatial arrangement and orientation in relation to patterns of yin and yang and the flow of energy (qi); the favorable or unfavorable effects are taken into consideration in designing and siting buildings and graves and furniture
    pillar of Islam
    (Islam) one of the five religious obligations accepted by all Muslims
    type of:
    generalisation, generality, generalization
    an idea or conclusion having general application
  2. noun
    a basic truth or law or assumption
    “the principles of democracy”
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    a guiding principle
    basic principle, basics, bedrock, fundamental principle, fundamentals
    principles from which other truths can be derived
    the principles that guide reasoning within a given field or situation
    pleasure principle, pleasure-pain principle, pleasure-unpleasure principle
    (psychoanalysis) the governing principle of the id; the principle that an infant seeks gratification and fails to distinguish fantasy from reality
    reality principle
    (psychoanalysis) the governing principle of the ego; the principle that as a child grows it becomes aware of the real environment and the need to accommodate to it
    the principle of revolt against constituted authority
    (physics) the maintenance of a certain quantities unchanged during chemical reactions or physical transformations
    the ultimate principle of the universe
    ABC, ABC's, ABCs, alphabet, first principle, first rudiment, rudiment
    the elementary stages of any subject (usually plural)
    conservation of charge, conservation of electricity
    the principle that the total electric charge of a system remains constant despite changes inside the system
    conservation of energy, first law of thermodynamics, law of conservation of energy
    the fundamental principle of physics that the total energy of an isolated system is constant despite internal changes
    conservation of mass, conservation of matter, law of conservation of mass, law of conservation of matter
    a fundamental principle of classical physics that matter cannot be created or destroyed in an isolated system
    conservation of momentum
    the principle that the total linear momentum in a closed system is constant and is not affected by processes occurring inside the system
    conservation of parity, mirror symmetry, parity, space-reflection symmetry
    (physics) parity is conserved in a universe in which the laws of physics are the same in a right-handed system of coordinates as in a left-handed system
    type of:
    law, natural law
    a rule or body of rules of conduct inherent in human nature and essential to or binding upon human society
  3. noun
    a rule or standard especially of good behavior
    “a man of principle
    “he will not violate his principles
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    accounting principle, accounting standard
    a principle that governs current accounting practice and that is used as a reference to determine the appropriate treatment of complex transactions
    chivalry, knightliness
    the medieval principles governing knighthood and knightly conduct
    ethic, moral principle, value orientation, value-system
    the principles of right and wrong that are accepted by an individual or a social group
    the principles and ideals associated with classical Greek civilization
    judicial doctrine, judicial principle, legal principle
    (law) a principle underlying the formulation of jurisprudence
    an ethical or moral principle that inhibits action
    the principles of a body of 19th century English reformers who advocated better social and economic conditions for working people
    jus sanguinis
    the principle that a person's nationality at birth is the same as that of his natural parents
    jus soli
    the principle that a person's nationality at birth is determined by the place of birth
    pre-emption, preemption
    the judicial principle asserting the supremacy of federal over state legislation on the same subject
    relation, relation back
    (law) the principle that an act done at a later time is deemed by law to have occurred at an earlier time
    type of:
    an ideal accepted by some individual or group
  4. noun
    rule of personal conduct
    synonyms: precept
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    higher law
    a principle that takes precedent over the laws of society
    moral principle
    the principle that conduct should be moral
    hypothetical imperative
    a principle stating the action required to attain a desired goal
    caveat emptor
    a commercial principle that without a warranty the buyer takes upon himself the risk of quality
    categorical imperative
    the moral principle that behavior should be determined by duty
    type of:
    prescript, rule
    prescribed guide for conduct or action
  5. noun
    a rule or law concerning a natural phenomenon or the function of a complex system
    “the principle of the conservation of mass”
    “the principle of jet propulsion”
    synonyms: rule
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    Gestalt law of organization, Gestalt principle of organization
    a principle of Gestalt psychology that identifies factors leading to particular forms of perceptual organization
    Le Chatelier principle, Le Chatelier's law, Le Chatelier's principle, Le Chatelier-Braun principle
    the principle that if any change is imposed on a system that is in equilibrium then the system tends to adjust to a new equilibrium counteracting the change
    Gresham's Law
    (economics) the principle that when two kinds of money having the same denominational value are in circulation the intrinsically more valuable money will be hoarded and the money of lower intrinsic value will circulate more freely until the intrinsically more valuable money is driven out of circulation; bad money drives out good; credited to Sir Thomas Gresham
    mass-energy equivalence
    (physics) the principle that a measured quantity of mass is equivalent (according to relativity theory) to a measured quantity of energy
    Naegele's rule
    rule for calculating an expected delivery date; subtract three months from the first day of the last menstrual period and add seven days to that date
    Occam's Razor, Ockham's Razor, law of parsimony, principle of parsimony
    the principle that entities should not be multiplied needlessly; the simplest of two competing theories is to be preferred
    principle of equivalence
    (physics) the principle that an observer has no way of distinguishing whether his laboratory is in a uniform gravitational field or is in an accelerated frame of reference
    principle of liquid displacement
    (hydrostatics) the volume of a body immersed in a fluid is equal to the volume of the displaced fluid
    Huygens' principle of superposition, principle of superposition
    the displacement of any point due to the superposition of wave systems is equal to the sum of the displacements of the individual waves at that point
    principle of superposition, superposition, superposition principle
    (geology) the principle that in a series of stratified sedimentary rocks the lowest stratum is the oldest
    mass action, mass-action principle
    (neurology) the principle that the cortex of the brain operates as a coordinated system with large masses of neural tissue involved in all complex functioning
    localisation, localisation of function, localisation principle, localization, localization of function, localization principle
    (physiology) the principle that specific functions have relatively circumscribed locations in some particular part or organ of the body
    lateralisation, laterality, lateralization
    localization of function on either the right or left sides of the brain
    closure, law of closure
    a Gestalt principle of organization holding that there is an innate tendency to perceive incomplete objects as complete and to close or fill gaps and to perceive asymmetric stimuli as symmetric
    common fate, law of common fate
    a Gestalt principle of organization holding that aspects of perceptual field that move or function in a similar manner will be perceived as a unit
    continuation, good continuation, law of continuation
    a Gestalt principle of organization holding that there is an innate tendency to perceive a line as continuing its established direction
    law of proximity, proximity
    a Gestalt principle of organization holding that (other things being equal) objects or events that are near to one another (in space or time) are perceived as belonging together as a unit
    law of similarity, similarity
    a Gestalt principle of organization holding that (other things being equal) parts of a stimulus field that are similar to each other tend to be perceived as belonging together as a unit
    type of:
    law, law of nature
    a generalization that describes recurring facts or events in nature
  6. noun
    (law) an explanation of the fundamental reasons (especially an explanation of the working of some device in terms of laws of nature)
    “the principles of internal-combustion engines”
    synonyms: rationale
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    a rationale for dialectical materialism based on change through the conflict of opposing forces
    type of:
    thought that makes something comprehensible
Commonly confused words

principal / principle

If offered a choice, would you rather have principles or principals?

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