(1)   An outward appearance
"He made a good impression"
"I wanted to create an impression of success"
"She retained that bold effect in her reproductions of the original painting"
(2)   (of a law) having legal validity
"The law is still in effect"
(3)   An impression (especially one that is artificial or contrived)
"He just did it for effect"
(4)   The central meaning or theme of a speech or literary work
(5)   A phenomenon that follows and is caused by some previous phenomenon
"The magnetic effect was greater when the rod was lengthwise"
"His decision had depressing consequences for business"
"He acted very wise after the event"
(6)   A symptom caused by an illness or a drug
"The effects of sleep loss"
"The effect of the anesthetic"


(7)   Produce
"The scientists set up a shock wave"


For noun: From (French: effet), from < , pp. ; see effect as a verb.

For verb: From , pp. of < + ; see fact and cf. affect, infect.


  1. The result or outcome of a cause. See usage notes below.
    The effect of the hurricane was a devastated landscape.
  2. An illusion produced by technical means (as in "special effect")
    The effect of flying was most convincing.
  3. An alteration in sound after it has been produced by an instrument.
    I use an echo effect here to make the sound more mysterious.
  4. A device for producing an alteration in sound produced by an instrument.
    I just bought a couple of great effects.
  5. The state of being binding and enforceable, as in a rule, policy, or law.
    The new law will come into effect on the first day of next year.
  6. A scientific phenomenon, usually named after its discoverer.
    Doppler effect
  7. Belongings, usually as personal effects.

Usage notes

The homophones “affect” and “effect” can both be used as nouns or verbs, but when used as a noun the word affect is limited to uses in the psychology field, and the above definitions for effect are much more common. See also the usage notes as a verb below.


  1. To make or bring about; to implement.
    The best way to effect change is to work with existing stakeholders.

Usage notes

Effect is often confused with “affect”. The latter is used to convey the influence over existing ideas, emotions and entities; the former indicates the manifestation of new or original ideas or entities:
  • “...new governing coalitions have effected major changes” indicates that major changes were made as a result of new governing coalitions.
  • “...new governing coalitions have affected major changes” indicates that before new governing coalitions, major changes were in place, and that the new governing coalitions had some influence over these existing changes.

Related terms