The noun affair has 3 senses (first 3 from tagged texts)
1. (23) matter, affair, thing -- (a vaguely specified concern; "several matters to attend to"; "it is none of your affair"; "things are going well")
2. (5) affair, affaire, intimacy, liaison, involvement, amour -- (a usually secretive or illicit sexual relationship)
3. (4) affair, occasion, social occasion, function, social function -- (a vaguely specified social event; "the party was quite an affair"; "an occasion arranged to honor the president"; "a seemingly endless round of social functions")