Function
Social gathering, social occasion, social function, get-together, reunion, jamboree, at-home, social, ball, frolic, carouse, hoedown, bake, levee, corroboree, luau, simcha, shindig, rave, beer-up, do, bop, whoopee, rave-up, knees-up, beano, jolly, hooley, blast, kegger, rage, jollo, jol, squeeze, gathering, social event, function, celebration, festivity, reception, soirée, dance, ceilidh, carousal, fete, shower, cookout, keg party, bashment, tertulia, bash, shindy, blowout, disco, shebang, hop, after-party, thrash, beanfeast, bunfight, lig, crack, wingding, shivoo, ding, rort, squash, and ding-dong.
Grouping
Faction, group, side, affiliation, coalition, cabal, bloc, set, sect, political party, grouping, alliance, association, movement, junta, camp, and caucus.
Company
Somebody
Person, human being, someone, individual, somebody, and character.
Celebrate
Celebrate, enjoy oneself, have a good/wild time, carouse, go out on the town, whoop it up, make whoopee, live it up, go on a bender, go on a spree, have fun, have a party, rave it up, make merry, paint the town red, let one's hair down, have a night on the tiles, have a ball, push the boat out, and jol.