verb (1)
af·​fect | \ ə-ˈfekt How to pronounce affect (audio) , a- \
affected; affecting; affects

Definition of affect

 (Entry 1 of 3)

transitive verb

: to produce an effect upon (someone or something):
a : to act on and cause a change in (someone or something) Rainfall affects plant growth. areas to be affected by highway construction The protein plays a central role in metabolism … which in turn affects the rate of aging.— Stephen S. Hall The 1883 eruption of Krakatau in what is now Indonesia affected global sunsets for years …— Evelyn Browning Garriss Before the 1980s it was not at all clear how nicotine affected the brain.— Cynthia Kuhn et al.
b : to cause illness, symptoms, etc., in (someone or something) a disease that affects millions of patients each year … the syndrome can affect the pancreas, which produces insulin …— H. Lee Kagan
c : to produce an emotional response in (someone) an experience that affected him powerfully … she traveled to Cuba and was deeply affected by what she saw.— Elsa Dixler
d : to influence (someone or something) trying not to let emotions affect their decision


verb (2)
af·​fect | \ ə-ˈfekt How to pronounce affect (audio) , a- \
affected; affecting; affects

Definition of affect (Entry 2 of 3)

transitive verb

1 : to put on a false appearance of (something) : to pretend to feel, have, or do (something) : feign affect indifference affect surprise He affected a French accent. … Fermi often affected an aversion to abstract mathematics.— Ed Barbeau But he affected not to hear …— Edith Wharton
2a : to often or usually wear or have (something) affect brightly colored clothing Chang affected the beard and long robe of an ancient scholar …— Constance A. Bond : to be given to (a preferred style of dress, speech, etc.) affect a precise way of speaking
b : to make a display of liking or using (something) : to ostentatiously cultivate or claim (a quality, attitude, etc.) affect a worldly manner It was the habit of the moment at Oxford to affect irreverence.— T. B. Costain
3 archaic : to have affection for : to feel love or tender attachment for (someone or something) As for Queen Katharine, he rather respected than affected, rather honored than loved her.— Thomas Fuller I affected Georgette; she was a sensitive and a loving child: to hold her in my lap, or carry her in my arms, was to me a treat.— Charlotte Bronte
4 archaic : to tend to have (a specified characteristic or quality) … the drops of every fluid affect a round figure by the mutual attraction of their parts …— Sir Isaac Newton
5 archaic : to often or usually spend time at (a place) or with (a person or group) : frequent … what birds affect that particular brake …— Thomas Hardy Do not affect the society of your inferiors in rank, nor court that of the great.— William Hazlitt
6 archaic : to aspire to : to try to attain (something, such as power) … this proud man affects imperial sway.— John Dryden


af·​fect | \ ˈa-ˌfekt How to pronounce affect (audio) \
plural affects

Definition of affect (Entry 3 of 3)

1 [German Affekt, borrowed from Latin affectus] psychology
a : a set of observable manifestations of an experienced emotion : the facial expressions, gestures, postures, vocal intonations, etc., that typically accompany an emotion Evidence from several clinical groups indicates that reduced accuracy in decoding facial affect is associated with impaired social competence.— Suzane Vassallo et al. … patients … showed perfectly normal reactions and affects— Oliver Sacks Other victims of schizophrenia sometimes lapse into flat affect, a zombielike state of apparent apathy.— David G. Myers
b : the conscious emotion that occurs in reaction to a thought or experience Positive affect encompasses all good emotions, such as joy, bliss, love, and contentment.— Roy F. Baumeister and Brad J. Bushman Killing and meaningless mass murder without affect, as the psychologists say, … have become too frequent occurrences in contemporary life.— Barbara W. Tuchman
2 obsolete : feeling, affection For every man with his affects is born, / Not by might mast'red, but by special grace.— William Shakespeare

Other Words from affect

Verb (1)

affectability \ ə-​ˌfek-​tə-​ˈbi-​lə-​tē How to pronounce affect (audio) , a-​ \ noun
affectable \ ə-​ˈfek-​tə-​bəl How to pronounce affect (audio) , a-​ \ adjective

Choose the Right Synonym for affect

Verb (1)

affect, influence, touch, impress, strike, sway mean to produce or have an effect upon. affect implies the action of a stimulus that can produce a response or reaction. the sight affected her to tears influence implies a force that brings about a change (as in nature or behavior). our beliefs are influenced by our upbringing touch may carry a vivid suggestion of close contact and may connote stirring, arousing, or harming. plants touched by frost his emotions were touched by her distress impress stresses the depth and persistence of the effect. only one of the plans impressed him strike, similar to but weaker than impress, may convey the notion of sudden sharp perception or appreciation. struck by the solemnity of the occasion sway implies the acting of influences that are not resisted or are irresistible, with resulting change in character or course of action. politicians who are swayed by popular opinion

Verb (2)

assume, affect, pretend, simulate, feign, counterfeit, sham mean to put on a false or deceptive appearance. assume often implies a justifiable motive rather than an intent to deceive. assumed an air of cheerfulness around the patients affect implies making a false show of possessing, using, or feeling. affected an interest in art pretend implies an overt and sustained false appearance. pretended that nothing had happened simulate suggests a close imitation of the appearance of something. cosmetics that simulate a suntan feign implies more artful invention than pretend, less specific mimicry than simulate. feigned sickness counterfeit implies achieving the highest degree of verisimilitude of any of these words. an actor counterfeiting drunkenness sham implies an obvious falseness that fools only the gullible. shammed a most unconvincing limp

Frequently Asked Questions About affect

What is the difference between affect and effect?

Both affect and effect can function as a noun or a verb. However, affect is most often found as a verb (“to produce an influence upon or alteration in”), and effect as a noun ("a change that results when something is done or happens”). For example, we can say that something that affects a person has an effect on them.

What is the difference between affection and affectation?

The more familiar word, affection, in modern use most often means "a feeling of liking and caring for someone or something." Affectation may be defined as "speech or conduct not natural to oneself," as in "He was born and raised in Baltimore, so his British accent seemed like an affectation."

Is affect a noun or a verb?

Affect is both a noun and a verb, but the verb is far more common; it means "to act on or change someone or something," as in "The change will affect everyone." The noun affect is used primarily in psychology contexts to refer to the facial expressions, gestures, postures, vocal intonations, etc., that typically accompany an emotion, as in "The patient had a flat affect."

Examples of affect in a Sentence

Verb (1) As strange as this sounds, the negative karma probably affected the actual games, the way a gambler who constantly dwells on his bad luck can derail an entire blackjack table. — Bill Simmons, ESPN, 24 June 2002 The Paris adventures of various Russians, including a romance for Dontsov, affect both the newly democratized ones and hard-line party members. — Stanley Kauffmann, New Republic, 27 Feb. 1995 These programs, known as secret warranties or silent recalls, often involve a problem that affects a vehicle's safety or performance but that isn't the cause of a formal Federal recall. Consumer Reports, December 1993 Verb (2) She pauses and affects the more dramatic tone of a veteran actress. — Chris Mundy, Rolling Stone, 15 June 1995 She doesn't put herself down, but she does affect a languid Valley Girl drawl to offset the sharpness of her observations … — Ken Tucker, Entertainment Weekly, 7 Oct. 1994 That is all I have, I said, affecting a pathos in my voice. — Flann O'Brian, At Swim-Two-Birds, 1939 Noun There's a good plot and good writing here, but Mallory's gender neutrality, conspicuous in her lack of affect, makes her seem like a comic-book character. — Cynthia Crossen, Wall Street Journal, 5 Oct. 1994 Many of these young killers display an absence of what psychiatrists call affect. They show no discernible emotional reaction to what they have done. — Richard Stengel, Time, 16 Sept. 1985 The way people respond to this is sometimes called "depressed affect"—a sort of mental shifting into neutral that psychologists say also happens to prisoners of war, submarine crews, and other people in confined situations with little stimulus. — Susan West, Science 84, January/February 1984 See More
Recent Examples on the Web: Verb Her attorneys did not immediately return a phone call and email for comment on how Tuesday’s verdict may affect their case. Washington Post, 10 May 2022 The holiday’s celebration is particularly significant in today’s political climate, which includes an attack on voting rights, which disproportionately affect Black residents, according to the resolution. Ted Glanzer, Hartford Courant, 10 May 2022 Another question is how the record revenues affect estimates for when the federal government is likely to hit the statutory limit, which now stands at just under $31.4 trillion. Laura Davison, Fortune, 9 May 2022 That may be changing in a time of rising worker power, and growing expectations that executives affect some measure of empathy, or become the subject of a disparaging prestige television series. Tim Fernholz, Quartz, 7 May 2022 Tell us more about how the changing gas cloud our solar system is moving through affect life on Earth. Jamie Carter, Forbes, 7 May 2022 Only a fraction of that will come from public sources, but the incentives, goals and regulations politicians set strongly affect private investment, risks and returns. Rochelle Toplensky, WSJ, 6 May 2022 Massachusetts requires public employees to file disclosures when seeking a new job if their public duties affect or involve a potential employer. Globe Staff,, 6 May 2022 In Alabama, school systems are mainly supported through state tax funding, but local property values affect that support. al, 5 May 2022 See More

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'affect.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

First Known Use of affect

Verb (1)

15th century, in the meaning defined above

Verb (2)

15th century, in the meaning defined at sense 6


14th century, in the meaning defined at sense 2

History and Etymology for affect

Verb (1)

Middle English affecten, borrowed from Latin affectus, past participle of afficere "to produce an effect on, exert an influence on," from ad- ad- + facere "to do, make, bring about" — more at fact

Verb (2)

Middle English affecten "to desire," borrowed from Anglo-French affeter, affecter "to change, seek after," borrowed from Latin affectāre "to try to accomplish, strive after, pretend to have," frequentative derivative of afficere "to produce an effect on, exert an influence on" — more at affect entry 1


Middle English, "capacity for emotion, emotion, desire, will," borrowed from Latin affectus "mental state, mood, feeling, affection," from afficere "to produce an effect on, exert an influence on" + -tus, suffix of verbal action — more at affect entry 1

Learn More About affect

Time Traveler for affect

Time Traveler

The first known use of affect was in the 14th century

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Statistics for affect

Last Updated

15 May 2022

Cite this Entry

“Affect.” Dictionary, Merriam-Webster, Accessed 19 May. 2022.

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More Definitions for affect


af·​fect | \ ə-ˈfekt How to pronounce affect (audio) \
affected; affecting

Kids Definition of affect

 (Entry 1 of 2)

: to pretend that a false behavior or feeling is natural or genuine She affected surprise upon hearing the news.


affected; affecting

Kids Definition of affect (Entry 2 of 2)

1 : to have an effect on I hope this disagreement won't affect our friendship. The oceans are affected by the moon.
2 : to cause strong emotions in … the Tin Woodman … was strongly affected by this sad speech.— L. Frank Baum, The Marvelous Land of Oz
3 : to cause illness in Rabies can affect dogs and cats.


af·​fect | \ ˈaf-ˌekt How to pronounce affect (audio) \

Medical Definition of affect

 (Entry 1 of 2)

: the conscious subjective aspect of an emotion considered apart from bodily changes also : a set of observable manifestations of a subjectively experienced emotion … patients … showed perfectly normal reactions and affects— Oliver Sacks


transitive verb
af·​fect | \ ə-ˈfekt, a- How to pronounce affect (audio) \

Medical Definition of affect (Entry 2 of 2)

: to produce an effect upon especially : to produce a material influence upon or alteration in paralysis affected his limbs

More from Merriam-Webster on affect

Nglish: Translation of affect for Spanish Speakers

Britannica English: Translation of affect for Arabic Speakers


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