From Middle English afere, affere, from Old French afaire, from a- + faire ("to do"), from Latin ad- + facere ("to do").

• (RP) IPA: /əˈfɛə/
• (America) IPA: /əˈfɛɹ/, /əˈfɛɚ/

affair (plural affairs)

1. (often in the plural) Something which is done or is to be done; business of any kind, commercial, professional, or public.

   Synonyms: matter, concern

   a difficult affair to manage

2. Any proceeding or action which it is wished to refer to or characterize vaguely.

   an affair of honor ― a duel

   an affair of love ― an intrigue

3. (military) An action or engagement not of sufficient magnitude to be called a battle.
4. A material object (vaguely designated).

   He used a hook-shaped affair with a long handle to unlock the car.

   • 1899 February, Joseph Conrad, “The Heart of Darkness”, in Blackwood's Edinburgh Magazine, volume CLXV, number M, New York, N.Y.: The Leonard Scott Publishing Company, […], →OCLC ↗, part I, page 200 ↗:

     She wore a starched white affair on her head, had a wart on one cheek, and silver-rimmed spectacles hung on the tip of her nose.

   • 1907 August, Robert W[illiam] Chambers, chapter I, in The Younger Set, New York, N.Y.: D. Appleton & Company, →OCLC ↗:

     The house was a big elaborate limestone affair, evidently new. Winter sunshine sparkled on lace-hung casement, on glass marquise, and the burnished bronze foliations of grille and door.

5. An adulterous relationship, chiefly of a married person. (from affaire de cœur, affair of the heart).

   When Martin's wife found out about his affair with her best friend, she asked for a divorce.

   Mary had an affair with a woman from the gym.

   • 1938, Norman Lindsay, Age of Consent, 1st Australian edition, Sydney, N.S.W.: Ure Smith, published 1962, →OCLC ↗, page 82:

     "Mean to say you been havin' an affair with Mrs. Peabody?"

6. An otherwise illicit romantic relationship, such as with someone who is not one's regular partner (boyfriend, girlfriend).

   Jerry's girlfriend said she wanted to go steady, but she was in an affair with one of his team-mates.

7. A person with whom someone has an adulterous relationship.
8. A party or social gathering, especially of a formal nature.
9. (slang, now, rare) The (male or female) genitals.
   • 1749, [John Cleland], “(Please specify the letter or volume)”, in Memoirs of a Woman of Pleasure [Fanny Hill], London: […] [Thomas Parker] for G. Fenton [i.e., Fenton and Ralph Griffiths] […], →OCLC ↗:

     [S]he, with the greatest effrontery imaginable, unbuttons his breeches, and removing his shirt, draws out his affair, so shrunk and diminished that I could not but remember the difference, now cresfallen, or just faintly lifting its head.

• German: Angelegenheit
• Italian: affare
• Portuguese: negócio, afazer
• Russian: де́ло
• Spanish: negocio

• German: Angelegenheit
• Portuguese: assunto, caso, coisa, negócio
• Russian: де́ло
• Spanish: asunto

• German: Scharmützel
• Russian: боестолкнове́ние

• German: Ding
• Portuguese: negócio
• Russian: штуко́вина
• Spanish: asunto

• French: aventure, liaison
• German: Beziehung, Affäre, Liebesaffäre, Verhältnis, Liebesverhältnis, Liebelei, Liaison, Liebschaft, Liebesangelegenheit, Liebesbeziehung, Liebesabenteuer, Gspusi (mainly Austrian, S. German, coll.)
• Portuguese: caso
• Russian: рома́н
• Spanish: asunto, rollo, amorío, aventura, devaneo, escarceo amoroso, lío de faldas

• Russian: причиндалы
• Spanish: partes