featherbrained

Từ điển WordNet v3.1 - WordNet Dictionary

adjective

lacking seriousness;
given to frivolity
- a dizzy blonde
- light-headed teenagers
- silly giggles
• Syn:
airheaded, dizzy, empty-headed, giddy, light-headed,
lightheaded, silly
• Similar to:
frivolous
• Derivationally related forms:
silliness (for: silly), lightheadedness (for: lightheaded), giddiness (for: giddy)