[ 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.

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

usage note for 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, adjective af·fect·a·bil·i·ty, noun

Definition for affect (2 of 2)

affect 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

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

usage note for affect

See affect1.


af·fect·er, noun

Example sentences from the Web for affect

British Dictionary definitions for affect (1 of 2)

affect 1

verb (əˈfɛkt) (tr)

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

noun (ˈæfɛkt, əˈfɛkt)

psychol the emotion associated with an idea or set of ideas See 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)

affect 2
/ (əˈfɛkt) /

verb (mainly tr)

to put on an appearance or show of; make a pretence of to affect ignorance
to imitate or assume, esp pretentiously to affect an accent
to have or use by preference she always affects funereal clothing
to adopt the character, manner, etc, of he was always affecting the politician
(of plants or animals) to live or grow in penguins affect an arctic climate
to incline naturally or habitually towards falling 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

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.