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verb (1)

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

transitive verb

: to produce an effect upon (someone or something):
: 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.
: 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
: 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
: to influence (someone or something)
trying not to let emotions affect their decision
affectability noun
affectable adjective


2 of 3

verb (2)

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

transitive verb

: 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
: 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
: 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
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
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
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
archaic : to aspire to : to try to attain (something, such as power)
… this proud man affects imperial sway.John Dryden


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af·​fect ˈa-ˌfekt How to pronounce affect (audio)
plural affects
[German Affekt, borrowed from Latin affectus] psychology
: 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 affectsOliver Sacks
Other victims of schizophrenia sometimes lapse into flat affect, a zombielike state of apparent apathy.David G. Myers
: 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
obsolete : feeling, affection
For every man with his affects is born, / Not by might mast'red, but by special grace.William Shakespeare
Effect vs. Affect: Usage Guide

Effect and affect are often confused because of their similar spelling and pronunciation. The verb affect entry 2 usually has to do with pretense.

she affected a cheery disposition despite feeling down

The more common verb affect entry 1 denotes having an effect or influence.

the weather affected everyone's mood

The verb effect goes beyond mere influence; it refers to actual achievement of a final result.

the new administration hopes to effect a peace settlement

The uncommon noun affect, which has a meaning relating to psychology, is also sometimes mistakenly used for the very common effect. In ordinary use, the noun you will want is effect.

waiting for the new law to take effect
the weather had an effect on everyone's mood

Frequently Asked Questions

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."

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

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
their son claims that scary movies don't affect him in the least fortunately, hurricane season doesn't affect the West Coast 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
she affected complete unawareness that we were talking about her, though she must have overheard a power couple known to affect all the fancy parties in town
Recent Examples on the Web
The Hobbs Act prohibits actual or attempted robbery that affects interstate commerce and that involves the taking of property from another person by means of actual or threatened force or violence. Carol Robinson |, al, 7 Apr. 2023 Julia Orzol did a little of everything for the Badgers There aren’t many players on the team that affect the game in as many ways as Julia Orzol. Mark Stewart, Journal Sentinel, 6 Apr. 2023
Peanut allergies affect approximately 6.1 million Americans. Brandi Jones, Msn-Ed, Health, 13 July 2024 Several relief groups have since sprung into action to help those affected in Texas. Haadiza Ogwude, The Enquirer, 12 July 2024 See all Example Sentences for affect 

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'affect.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History


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

First Known Use

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

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

Dictionary Entries Near affect

Cite this Entry

“Affect.” Dictionary, Merriam-Webster, Accessed 24 Jul. 2024.

Kids Definition


1 of 2 verb
af·​fect ə-ˈfekt How to pronounce affect (audio)
: to show a liking for : fancy
affect flashy clothes
: feign sense 1, pretend
affect indifference


2 of 2 verb
: to produce an effect upon: as
: to produce a significant influence upon or change in
paralysis affected his limbs
: to act upon (as a person or a person's feelings) so as to cause a response
the criticism affected her deeply

Medical Definition


1 of 2 noun
af·​fect ˈaf-ˌekt How to pronounce affect (audio)
: 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 affectsOliver Sacks


2 of 2 transitive verb
af·​fect ə-ˈfekt, a- How to pronounce affect (audio)
: to produce an effect upon
especially : to produce a material influence upon or alteration in
paralysis affected his limbs

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