Etymology: (1375–1425; ME sely, orig., blessed, happy, guileless, OE gesaelig happy, der. of sael happiness; c. D zalig, G selig)
Definition of 'SILLY'
Princeton's WordNet
1. (adj)silly a word used for misbehaving children "don't be a silly"
2. (adj)cockamamie, cockamamy, goofy, sappy, silly, wacky, whacky, zany ludicrous, foolish "gave me a cockamamie reason for not going"; "wore a goofy hat"; "a silly idea"; "some wacky plan for selling more books"
3. (adj)airheaded, dizzy, empty-headed, featherbrained, giddy, light-headed, lightheaded, silly lacking seriousness; given to frivolity "a dizzy blonde"; "light-headed teenagers"; "silly giggles"
4. (adj)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
5. (adj)punch-drunk, silly, slaphappy dazed from or as if from repeated blows "knocked silly by the impact"; "slaphappy with exhaustion"
5. (noun)SILLY weak in intellect; destitute of ordinary strength of mind; foolish; witless; simple; as, a silly woman
6. (noun)SILLY proceeding from want of understanding or common judgment; characterized by weakness or folly; unwise; absurd; stupid; as, silly conduct; a silly question