affair, bash, binge, blast, blowout, do, event, fete(or fête), function, get-together, party, powwow(informal, now offensive), reception

benefit, fund-raiserball, dance, formal, promcelebration, gala, occasionbacchanal, bacchanalia, orgy, saturnaliabake, clambake, cocktail party, hen party, house party, housewarming, icebreaker, kaffeeklatsch, kegger(also keg party), klatch(also klatsch), masquerade, meet and greet, mixer, salon, shower, social, soiree(or soirée), stag, supper, symposium, tea, tea party