Giddy is the light, swimming feeling in your head when the world will not stay still. Standing up too fast out of a hot bath, stepping off a roundabout, looking down from a ladder and gripping it harder than you need to.
The second giddy is not about balance but about excitement — giddy with relief, giddy with happiness, a giddy teenager who cannot sit down for two minutes. That sense carries a hint of silliness, so calling a grown adult giddy is gentle mockery. Heights get the word too: the giddy heights of the top of the league, the giddy pace of the first month. The adverb is giddily and the noun is giddiness, which is what a doctor writes down when you say dizzy. Dizzy is the plainer everyday word; giddy sounds more British and a little older.
1adjectivegiddyFeeling as if everything is spinning; unsteady on your feet.
“She sat down on the kerb, giddy from the heat.”
synonyms: dizzy, light-headed, faint
2adjectiveelatedExcited to the point of silliness.
“They came out of the cinema giddy and talking over each other.”
synonyms: elated, exhilarated
3adjectivemakingMaking you feel dizzy, through height or speed.
“The band rose to giddy heights in a single summer.”
Giddy once meant god-struck. Old English gidiġ described a person possessed by a demon or a spirit, from Proto-West Germanic *gudīg, literally possessed by a god, built from god plus an ending. Middle English gidi kept the madness and lost the god; from madness the word slid to foolishness, and from foolishness to the spinning head you get on a fairground ride.
Proto-Indo-European
*ǵʰew-
Proto-West Germanic
*gudīg — ghostly, spirited
Old English
gidiġ
Middle English
gidi
English, today
giddy
Built from
The adjective is derived from Middle English gidi, gedy, gydy (“demonically controlled or possessed; crazy, insane; foolish, idiotic, ridiculous, unwise; unsure; (rare) dizzy, shaky; (rare) of an animal: crazed, out of control; a fool”)gedi, gidie, gidy, gudi, gudiʒe, guidi, guydi, gydi, gydie, from Old English gidiġ, gydiġ (“possessed by a demon or spirit, insane, mad”), from Proto-West Germanic gudīg (“ghostly, spirited”) literally “possessed by a god or spirit”, from god (“god”) + -ig, -g. The English word is analysable as god + y. The noun and the verb are derived from the adjective.
Etymology from Wiktionary, CC BY-SA