Synonyms for Fun:

adj.

amusing (adjective)
Distracting, Light-hearted, hilarious, pleasing, enthralling, merry, diverting, stimulating, refreshing, jolly, relaxing, delightful, frivolous, rollicking, playful, entertaining, jocular, amusing, recreational, charming, beguiling.
good, happy (adjective)
amusing, entertaining, merry, enjoyable, pleasant, diverting.
pleasant (adjective)
enjoyable.

n.

cheerful, restful, attractive, lovely, nice. festivity, festival, fling, revel, festiveness, gaieties, giggle, revelry, merrymaking, laughter, jollity, conviviality, devilment. fool around, jest. act (noun)
merriment, playfulness.
amusement (noun)
game, pleasure, celebration, recreation, pastime, distraction, levity, amusement, Divertissement, refreshment, hilarity, diversion, jocularity, merriment, hobby, relaxation, entertainment, frivolity, tonic, whimsicality, Jolliness, sport, stimulation, humor, play.
amusement, play (noun)
jollity, jocularity, celebration, festivity, relaxation, jesting, pleasure, entertainment, pastime, game, merriment, playfulness, sport, merrymaking, joke, recreation, diversion, laughter, distraction.
banter (noun)
mockery.
communication (noun)
play, sport.
fun (noun)
diverting, amusive, playfulness, merriment, play, entertaining, sport, amusing.
laughter (noun)
hilarity.
make fun of (noun)
diverting, delightful, ridicule, entertaining, recreational, enjoyable, taunt, amusing.
merry (noun)
pleasant, enjoyable, happy.
merrymaking (noun)
revelry.
ridicule (noun)
insult, scorn, disgrace, travesty, ridicule, contempt, jesting, caricature, irreverence, flippancy, roast, humiliation, shame, taunt, deprecation, derision, denigration, indignity, sneering, abasement burlesque, joke, irony, mockery.

Other synonyms:

pleasant, jollity, festiveness, giggle. conviviality, festival. disport, revelry. festivity, fling. frolic
merrymaking.
Other relevant words:
wit, festiveness, fool around, laughter, festival, jest, disport, revelry, playfulness, happy, pleasant, conviviality, festivity, revel, jollity, enjoyable, giggle, amusive, merrymaking, clown, cheerful.

Usage examples for fun

  1. " I should think that would be kind of fun she said. – Gentle Julia by Booth Tarkington
  2. So we can't have any fun – The Little Colonel at Boarding-School by Annie Fellows Johnston
  3. I think it would be fun – Marjorie's Busy Days by Carolyn Wells