Look up affect in Wiktionary, the free dictionary.
When used as a descriptor or adjective, affect means to change, and usually refers to an emotion or symptom. Affected, when used in a description, refers to fake or intentionally assumed behaviour (a changed behaviour), i.e., an affected accent. Affect can refer to facial expression or demeanor.
In general, to affect refers to the influence a change has on something else. In this sense, it is often confused with to effect, which generally means either "to cause/make/create a change" or to the result of a change. When used as a verb, "effect" refers to the cause of a change, or as a synonym for "created" or "made" ("The governor effected a change in policy"); while "affect" refers to the consequences of that change ("The new policy really affected our family").
As a noun, "affect" may refer to an emotion or to a psychological/psychiatric state (see below). As an adjective, it may refer to an assumed pretense: "Her affected accent really had an effect on me"; "Her affected accent really affected my view of her".
Affect may refer to:
Blunted affect or affective flattening, a reduction in emotional reactivity.,
Labile affect, the unstable display of emotion.,
Affect display, signs of emotion, such as facial expression, vocalization, and posture,
Affective science, the scientific study of emotion,
Affect (linguistics), the grammar of expressing affect,
Affective computing, an area of research in computer science aiming to understand the emotional state of users,
Affekt, a German term often used in musical and other aesthetic theory
Doctrine of the affections, an important theory in the aesthetics of music,