[ verb uh-fekt; noun af-ekt ]
/ verb əˈfɛkt; noun ˈæf ɛkt /

verb (used with object)

to act on; produce an effect or change in: Cold weather affected the crops.
to impress the mind or move the feelings of: The music affected him deeply.
(of pain, disease, etc.) to attack or lay hold of.


Psychology. feeling or emotion.
Psychiatry. an expressed or observed emotional response: Restricted, flat, or blunted affect may be a symptom of mental illness, especially schizophrenia.
Obsolete. affection; passion; sensation; inclination; inward disposition or feeling.


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Origin of affect

1350–1400; Middle English <Latin affectus acted upon, subjected to; mental or emotional state (past participle and action noun of afficere), equivalent to af-af- + fec- (combining form of facere to make, do) + -tus action noun suffix or -tus past participle suffix

words often confused with affect

Affect1 and effect, each both noun and verb, share the sense of “influence,” and because of their similarity in pronunciation are sometimes confused in writing. As a verb affect1 means “to act on” or “to move” ( His words affected the crowd so deeply that many wept ); affect2 means “to pretend” or “to assume” ( new students affecting a nonchalance they didn't feel ). The verb effect means “to bring about, accomplish”: Her administration effected radical changes. The noun effect means “result, consequence”: the serious effects of the oil spill. The noun affect1 pronounced with the stress on the first syllable, is a technical term in psychology and psychiatry. Affect2 is not used as a noun.


af·fect·a·ble, adjectiveaf·fect·a·bil·i·ty, noun

Definition for affect (2 of 2)

[ uh-fekt ]
/ əˈfɛkt /

verb (used with object)

verb (used without object)

Obsolete. to incline, tend, or favor (usually followed by to): He affects to the old ways.

Origin of affect

First recorded in 1400–50; late Middle English, from Middle French affecter, from Latin affectāre “to strive after, feign” (frequentative of afficere “to do to”), equivalent to af-af- + fec- (see affect1) + -tāre frequentative suffix

synonym study for affect

1. See pretend.

words often confused with affect

See affect1.


af·fect·er, noun Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2020

Example sentences from the Web for affect

British Dictionary definitions for affect (1 of 2)


verb (əˈfɛkt) (tr)

to act upon or influence, esp in an adverse waydamp affected the sparking plugs
to move or disturb emotionally or mentallyher death affected him greatly
(of pain, disease, etc) to attack

noun (ˈæfɛkt, əˈfɛkt)

psychol the emotion associated with an idea or set of ideasSee also affection

Word Origin for affect

C17: from Latin affectus, past participle of afficere to act upon, from ad- to + facere to do

British Dictionary definitions for affect (2 of 2)

/ (əˈfɛkt) /

verb (mainly tr)

to put on an appearance or show of; make a pretence ofto affect ignorance
to imitate or assume, esp pretentiouslyto affect an accent
to have or use by preferenceshe always affects funereal clothing
to adopt the character, manner, etc, ofhe was always affecting the politician
(of plants or animals) to live or grow inpenguins affect an arctic climate
to incline naturally or habitually towardsfalling drops of liquid affect roundness

Word Origin for affect

C15: from Latin affectāre to strive after, pretend to have; related to afficere to affect 1
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Medical definitions for affect

[ ə-fĕkt ]


To have an influence on or affect a change in.
To attack or infect, as a disease.


Feeling or emotion, especially as manifested by facial expression or body language.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.