silly in WordNet English dictionary

1. lacking seriousness; given to frivolity
   "a dizzy blonde"; "light-headed teenagers"; "silly giggles"
   airheaded  dizzy  empty-headed  featherbrained  giddy  light-headed  lightheaded  silly 
   
2. ludicrous, foolish
   "gave me a cockamamie reason for not going"; "wore a goofy hat"; "a silly idea"; "some wacky plan for selling more books"
   cockamamie  cockamamy  goofy  sappy  silly  wacky  whacky  zany 
   
3. inspiring scornful pity
   "how silly an ardent and unsuccessful wooer can be especially if he is getting on in years"- Dashiell Hammett
   pathetic  ridiculous  silly 
   
4. dazed from or as if from repeated blows
   "knocked silly by the impact"; "slaphappy with exhaustion"
   punch-drunk  silly  slaphappy 
   

1. a word used for misbehaving children
   "don't be a silly"
   silly