adjective
1.
having a lightheartedly silly nature
tried to teach a bunch of giddy Girl Scouts how to make a fire
Synonyms: bird-witted, dizzy, empty-headed, featherbrained, flighty, fribble, fribbling, frivolous, harebrained, hoity-toity, light, light-headed, rattlebrained, scatterbrained, silly, skittish, volage, yeasty
Related Word: capricious, fickle, impulsive, whimsical; brainless, exuberant, thoughtless, witless
Idioms: giddy as a goose
Contrasted words: earnest, pensive, sedate, serious, sober, solemn, staid, thoughtful
2.
Synonyms: dizzy 2, light, light-headed, swimming, swimmy, vertiginous
Related Word: bemused, flustered
Idioms: going around in circles, like a chicken with its head cut off, seeing double