fun / fən/ • n. enjoyment, amusement, or lighthearted pleasure: the children were having fun in the play area anyone who turns up can join in the fun. ∎  a source of this: people-watching is great fun. ∎  playful behavior or good humor: she's full of fun. ∎  behavior or an activity that is intended purely for amusement and should not be interpreted as having serious or malicious purposes: it was nothing serious; they just enjoyed having some harmless fun. ∎  (of a place or event) providing entertainment or leisure activities for children: a 33-acre movie-themed fun park.• adj. (fun·ner fun·nest) inf. amusing, entertaining, or enjoyable: it was a fun evening what's the funnest part of wakeboarding for you?• v. inf. joke or tease: [intr.] no need to get sore—I was only funning | [tr.] they are just funning you. PHRASES: for fun (or for the fun of it) in order to amuse oneself and not for any more serious purpose.fun and games amusing and enjoyable activities: teaching isn't all fun and games.someone's idea of fun used to emphasize one's dislike for an activity or to mock someone else's liking for it: being stuck behind a desk all day isn't my idea of fun.in fun not intended seriously; as a joke: remember when you meet the press to say that your speech was all in fun.like fun dated an ironic exclamation of contradiction or disbelief in response to a statement.make fun of (or poke fun at) tease, laugh at, or joke about (someone) in a mocking or unkind way.not much (or a lot of) fun used to indicate that something strikes one as extremely unpleasant and depressing: it can't be much fun living next door to him.what fun! used to convey that an activity or situation sounds amusing or enjoyable.ORIGIN: late 17th cent. (denoting a trick or hoax): from obsolete fun ‘to cheat or hoax,’ dialect variant of late Middle English fon ‘make a fool of, be a fool,’ related to fon ‘a fool,’ of unknown origin. Compare with fond.