noun, noun which may take the genitive case particle 'no'
sanity; sound mind; consciousness; soberness
Refers to a mentally sound, rational, or conscious state. Often used in negative or questioning expressions like 正気じゃない or 正気か？, and in phrases like 正気に戻る (regain consciousness/sanity).
See also: 狂気
彼は正気を失っているように見えた。
He seemed to have lost his sanity.
そんな
Are you in your right mind, saying something like that?
Antonym; means madness or insanity, the opposite of 正気.
Compound of 正 (correct, proper) and 気 (spirit, mind). The exact historical derivation is uncertain, but the combination naturally conveys a proper state of mind.