Same word as party:

affair, amusement, at-home, ball, banquet, barbecue, bash, blowout, carousal, carousing, celebration, cocktails, coffee klatch, coming-out, dinner, diversion, do, entertainment, feast, festive occasion, festivity, fete, fun, function, gala, get-together, luncheon, movable feast, orgy, prom, reception, riot, shindig, social, soiree, splurge, spree, tea