light-headed

adjective

1. giddy, dizzy, or delirious: After two drinks Pat began to feel lightheaded.
2. having or showing a frivolous or volatile disposition; thoughtless: lightheaded persons.

adjective

1. frivolous in disposition or behaviour
2. giddy; feeling faint or slightly delirious

adj.also lightheaded, “dizzy,” 1530s; from light (adj.1) + head (n.). Related: Light-headedness.