Adjective lightheaded has 2 senses
- faint, light, swooning, light-headed, lightheaded - weak and likely to lose consciousness; "suddenly felt faint from the pain"; "was sick and faint from hunger"; "felt light in the head"; "a swooning fit"; "light-headed with wine"; "light-headed from lack of sleep"
Antonym: well (indirect, via ill)
- airheaded, dizzy, empty-headed, featherbrained, giddy, light-headed, lightheaded, silly - lacking seriousness; given to frivolity; "a dizzy blonde"; "light-headed teenagers"; "silly giggles"
Antonym: serious (indirect, via frivolous)
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