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1. Having or causing a whirling sensation; liable to falling
   "had a headache and felt giddy"; "a giddy precipice";
   - dizzy, woozy [informal], vertiginous
    
2. Lacking seriousness; given to frivolity
   "a giddy blonde";
   - airheaded, dizzy, empty-headed, featherbrained, light-headed, lightheaded, silly

1. Make or become dizzy

Derived forms: giddier, giddied, giddies, giddiest, giddying

See also: frivolous, ill, sick

Encyclopedia: Giddy