noun
play, game, sport, jest, amusement, relaxation, pastime, diversion, frolic, mirth, entertainment, recreation, solace, merriment, jollity, jollification, pleasure, good time, drollery, buffoonery, foolery, fooling, romping, joke, absurdity, playfulness, laughter, frolicsomeness, festivity, carnival, tomfoolery, escapade, antic, romp, gambol, prank, lark, comedy, banter, teasing, raillery, high jinks, celebration, holiday, rejoicing, good humor, joking, jocularity, enjoyment, gladness, good cheer, delight, glee, high glee, treat, hilarity, blitheness, joy, jocundity, joviality, time of one's life*, blast*, whoopee*, picnic*, riot*.
Antonyms unhappiness*, tedium, sorrow.
for<strong> or </strong>in fun
for amusement, not seriously, playfully, for no reason, for the fun of it, as a joke, for laughs, for kicks*; see also happily 2.
make fun of
