Definitions of silly:

• noun:   a word used for misbehaving children

  Example: "Don't be a silly"

• adjective:   dazed from or as if from repeated blows

  Example: "Knocked silly by the impact"

• adjective:   inspiring scornful pity

  Example: "How silly an ardent and unsuccessful wooer can be especially if he is getting on in years- Dashiell Hammett"

• adjective:   pungent adjectives of disesteem

  Example: "A silly idea"

• adjective:   lacking seriousness; given to frivolity

  Example: "Silly giggles"