effect

UK: /ɪˈfɛkt/ US: /ɪˈfɛkt/ ,(i fekt′)

WordReference Random House Learner's Dictionary of American English © 2025

ef•fect /ɪˈfɛkt/   n. 

1. [countable] something produced;
   a result or consequence.
2. [uncountable] power to produce results;
   force:
   The protest had no effect.
3. [uncountable] the state of being effective or operative;
   operation or execution:
   to bring a plan into effect.
4. a mental or emotional impression produced:
   [countable] He's trying to create a mottled effect with those odd colors.

v. [~ + object]

5. to produce as an effect;
   bring about;
   accomplish:
   to effect a change.

Idioms

6. Idioms in effect:
   • essentially;
     basically:
     in effect, a whole new way of rewarding workers.
   • operating or functioning;
     in force:
     The new law is in effect.
7. Idioms take effect, to go into operation;
   begin to function;
   start to produce a result:
   I could feel the whisky begin to take effect.

See -fec-.

WordReference Random House Unabridged Dictionary of American English © 2025

ef•fect  (i fekt′), n. 

1. something that is produced by an agency or cause;
   result;
   consequence:
   Exposure to the sun had the effect of toughening his skin.
2. power to produce results;
   efficacy;
   force;
   validity;
   influence:
   His protest had no effect.
3. the state of being effective or operative;
   operation or execution;
   accomplishment or fulfillment:
   to bring a plan into effect.
4. a mental or emotional impression produced, as by a painting or a speech.
5. meaning or sense;
   purpose or intention:
   She disapproved of the proposal and wrote to that effect.
6. the making of a desired impression:
   We had the feeling that the big, expensive car was only for effect.
7. an illusory phenomenon:
   a three-dimensional effect.
8. a real phenomenon (usually named for its discoverer):
   the Doppler effect.
9. Show Business See special effects. 
10. Idioms in effect:
    • for practical purposes;
      virtually:
      His silence was in effect a confirmation of the rumor.
    • essentially;
      basically.
    • operating or functioning;
      in force:
      The plan is now in effect.
11. Idioms take effect:
    • to go into operation;
      begin to function.
    • to produce a result:
      The prescribed medicine failed to take effect.

v.t. 

12. to produce as an effect;
    bring about;
    accomplish;
    make happen:
    The new machines finally effected the transition to computerized accounting last spring.

• Latin effectus the carrying out (of a task, etc.), hence, that which is achieved, outcome, equivalent. to effec- (variant stem of efficere to make, carry out; ef- ef- + -ficere, combining form of facere to do¹) + -tus suffix of verb, verbal action
• Middle English 1350–1400

ef•fect′i•ble, adj. 
Synonyms

• 1. outcome, issue.
  Effect, consequence(
  s),
  result refer to something produced by an action or a cause. An effect is that which is produced, usually more or less immediately and directly:
  The effect of morphine is to produce sleep.
  A consequence, something that follows naturally or logically, as in a train of events or sequence of time, is less intimately connected with its cause than is an effect:
  Punishment is the consequence of disobedience.
  A result may be near or remote, and often is the sum of effects or consequences as making an end or final outcome:
  The English language is the result of the fusion of many different elements.
• 12. achieve, realize, fulfill, perform, consummate.

Usage

See affect ¹.

Collins Concise English Dictionary © HarperCollins Publishers::

effect / ɪˈfɛkt/ noun

1. something that is produced by a cause or agent; result
2. power or ability to influence or produce a result; efficacy
3. the condition of being operative (esp in the phrases in or into effect)
4. take effect ⇒ to become operative or begin to produce results
5. basic meaning or purpose (esp in the phrase to that effect)
6. an impression, usually one that is artificial or contrived (esp in the phrase for effect)
7. a scientific phenomenon: the Doppler effect
8. in effect ⇒ in fact; actually
9. for all practical purposes
10. the overall impression or result

verb

1. (transitive) to cause to occur; bring about; accomplish

Etymology: 14th Century: from Latin effectus a performing, tendency, from efficere to accomplish, from facere to do

efˈfecter noun

efˈfectible adjective