amusement or enjoyment
a cause of this
good humour
derisive amusement; ridicule
a figure of fun
violent or excited activity or argument
They let a snake loose in the classroom; then the fun began
fun and games
confused activity, or trouble and difficulty
in fun
not intending harm or to be taken seriously
make fun of/poke fun at
to make (somebody or something) an object of amusement or ridicule
[dialect fun to hoax, perhaps alteration of Middle English fonnen, from fonne dupe; earlier history unknown]