Adjective silly has 4 senses
  1. cockamamie, cockamamy, goofy, sappy, silly, wacky, whacky, zany, unreasonable - pungent adjectives of disesteem; "gave me a cockamamie reason for not going"; "wore a goofy hat"; "a silly idea"; "some wacky plan for selling more books"
    Antonym: wise (indirect, via foolish)
  2. airheaded, dizzy, empty-headed, featherbrained, giddy, light-headed, lightheaded, silly - lacking seriousness; given to frivolity; "a dizzy blonde"; "light-headed teenagers"; "silly giggles"
    Antonym: serious (indirect, via frivolous)
  3. pathetic, ridiculous, silly - inspiring scornful pity; "how silly an ardent and unsuccessful wooer can be especially if he is getting on in years"- Dashiell Hammett
    Antonym: dignified (indirect, via undignified)
  4. punch-drunk, silly, slaphappy - dazed from or as if from repeated blows; "knocked silly by the impact"; "slaphappy with exhaustion"
    Antonyms: clearheaded, clear-thinking (indirect, via confused)
,Noun silly has 1 sense
  1. silly - a word used for misbehaving children; "don't be a silly"
    --1 is a kind of
    child, kid, youngster, minor, shaver, nipper, small fry, tiddler, tike, tyke, fry, nestling