affect

Etymology 1

From Middle English affecten, from Latin affectāre, from Latin affectus, the participle stem of Latin afficere (“to act upon, influence, affect, attack with disease”), from ad- + facere (“to make, do”).

verb

1. (transitive) To influence or alter.
   The experience affected me deeply.
   The heat of the sunlight affected the speed of the chemical reaction.
   Libertarian paternalism is the view that, because the way options are presented to citizens affects what they choose, society should present options in a way that “nudges” our intuitive selves to make choices that are more consistent with what our more deliberative selves would have chosen if they were in control. 2012-01, Steven Sloman, “The Battle Between Intuition and Deliberation”, in American Scientist, volume 100, number 1, page 74
2. (transitive) To move to emotion.
   He was deeply affected by the tragic ending of the play.
   A consideration of the rationale of our passions seems to me very necessary for all who would affect them upon solid and pure principles. 1757, Edmund Burke, A Philosophical Enquiry into the Origin of Our Ideas of the Sublime and Beautiful
3. (transitive, pathology) Of an illness or condition, to infect or harm (a part of the body).
   Hepatitis affects the liver.
4. (transitive, archaic) To dispose or incline.
5. (transitive, archaic) To tend to by affinity or disposition.
6. (transitive, archaic) To assign; to appoint.
7. (transitive, Scotland, law) To burden (property) with a fixed charge or payment, or other condition or restriction.

Etymology 2

From Middle English affecten, from Anglo-Norman affecter (“strive after”), Middle French affecter (“feign”), and their source, Latin affectāre (“to strive after, aim to do, pursue, imitate with dissimulation, feign”), frequentative of afficere (“to act upon, influence”) (see Etymology 1, above).

verb

1. (transitive) To make a show of; to put on a pretense of; to feign; to assume. To make a false display of.
   to affect ignorance
   to affect a British accent
   He managed to affect a smile despite feeling quite miserable.
   Careless she is with artful care, / Affecting to seem unaffected. a. 1729, William Congreve, A Hue and Cry After Fair Amoret
2. (obsolete, transitive) To aim for, to try to obtain.
   I seek the Vatican, and the palaces. I affect to be intoxicated with sights and suggestions, but I am not intoxicated. 1841, Ralph Waldo Emerson, “Self-Reliance”, in Essays: First Series
3. (transitive, rare) To feel affection for (someone); to like, be fond of.
4. (transitive, obsolete) To show a fondness for (something); to choose.
   1825, William Hazlitt, “On the Conduct of life: or Advice to a schoolboy” in Table-Talk Volume II, Paris: A. & W. Galignani, p. 284, Do not affect the society of your inferiors in rank, nor court that of the great.

Etymology 3

From Middle English affect, from Latin affectus, adfectus (“a state of mind or body produced by some (external) influence, especially sympathy or love”), from afficere (“to act upon, influence”).

noun

1. (psychology) A subjective feeling experienced in response to a thought or other stimulus; mood, emotion, especially as demonstrated in external physical signs.
   if we are afraid of robbers in a dream, the robbers are certainly imaginary, but the fear is real. This draws our attention to the fact that the development of affects [translating Affectentwicklung] in dreams is not amenable to the judgement we make of the rest of the dream-content …. 1999, Sigmund Freud, translated by Joyce Crick, The Interpretation of Dreams, Oxford, published 2008, page 62
   A third study demonstrated that the effects of self-affirmation on self-regulated performance were not due to positive affect. 2004, Jeffrey Greenberg, Thomas A Pyszczynski, Handbook of Experimental Existential Psychology, page 407
2. (obsolete) One's mood or inclination; mental state.
3. (obsolete) A desire, an appetite.