Affair

noun

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

   "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. 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."

5. An adulterous relationship. (from affaire de cœur).