godan verb (-ru), intransitive verb
to be one tile away from winning (mahjong)
Mahjong term: the state of needing only one more tile to complete a winning hand. Derived from 聴牌 (テンパイ).
See also: 聴牌
あと一牌でテンパる。
I'm one tile away from being ready to win.
godan verb (-ru), intransitive verb
to be at one's wits' end; to be about to lose it
Colloquial extension of the mahjong sense: describes a state of mental overload, panic, or extreme stress where one is about to snap.
仕事が多すぎてテンパってる。
I'm so swamped with work I'm about to lose it.
急に質問されてテンパった。
I panicked when I was suddenly asked a question.