mass noun
1- enjoyment, amusement, or light-hearted pleasure享乐, 娱乐; 乐趣：
the children were having fun in the play area.
孩子们正在玩耍区嬉戏。
1.1
- a source of this娱乐（或乐趣）的来源; 有趣的人（或事）：
peoplewatching is great fun.
观察人是一大乐趣。
1.2
- playful behaviour or good humour顽皮; 风趣：
she's full of fun.
她很风趣。
1.3
- behaviour or an activity that is intended purely for amusement and should not be interpreted as having serious or malicious purposes纯娱乐行为（或活动）, 逗乐：
the column's just a bit of fun.
这个专栏纯属消遣。
1
- informal amusing, entertaining, or enjoyable〈非正式〉有趣的; 令人愉快的; 快乐的：
it was a fun evening.
那是一个欢乐的夜晚。
1.1
- attrib.(of a place or event) providing entertainment or leisure activities for children（地点, 活动）为孩子提供娱乐（或休闲活动）的：
a school fun day.
学校的文娱活动日。
- informal, chiefly N. Amer. joke or tease〈非正式, 主北美〉开玩笑; 取笑：
no obj. no need to get sore - I was only funning不必窝火——我只是开开玩笑罢了
with obj. they are just funning you.他们在取笑你呢。
USAGE
The use of fun as an adjective meaning 'enjoyable', as in we had a fun evening is not fully accepted in standard English and should only be used in informal contexts. There are signs that this situation is changing, though, given the recent appearance in US English of comparative and superlative forms funner and funnest, formed as if fun were a normal adjective.
短语
for fun（或for the fun of it）
- in order to amuse oneself and not for any more serious purpose为了好玩儿, 闹着玩儿地。
fun and games
- amusing and enjoyable activities玩耍, 嬉戏：
teaching isn't all fun and games.
教学不是一天到晚玩耍找乐。
someone's idea of fun
- used to emphasize one's dislike for an activity or to mock someone else's liking for it［用于强调不喜欢某事或嘲讽他人对某事的喜欢］：
being stuck behind a desk all day isn't my idea of fun.
整天不能离开办公桌半步可不是好玩的。
in fun
- not intended seriously; as a joke不是当真的; 开玩笑的：
remember when you meet the press to say that your speech was all in fun.
你和新闻界人士见面时别忘了说清楚你那次讲话只是闹着玩儿的。
like fun
1
- dated, chiefly N. Amer. an ironic exclamation of contradiction or disbelief in response to a statement〈旧, 主北美, 讽〉决不会,哪里有这种事（表示反驳或不相信）。
2
- Brit. archaic vigorously or quickly〈英, 古〉有力地; 很快地：
the mill is blazing away like fun.
熊熊大火迅猛地吞噬着工厂。
make fun of
- tease, laugh at, or joke about (someone) in a mocking or unkind way取笑, 嘲弄（某人）。
not much （或a lot of） fun
- used to indicate that something strikes one as extremely unpleasant and depressing用于表示对某事感到极为不快极不愉快, 太令人沮丧：
it can't be much fun living next door to him.
与他为邻决非幸事。
what fun!
- used to convey that an activity or situation sounds amusing or enjoyable多么有趣！
词源
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.