midnight

(Hinduism) Yama, the Hindu god of death / (Buddhism) Short for 夜摩天 (Yamaten): Yama, the Buddhist ruler of 奈落 (Naraku, “Naraka, hell”)

late at night

a night owl (idiomatic)

(euphemistic) job in the nightlife / sex industry

(Internet slang, humorous, pun) Christmas Eve, as a night of sexual activity between young couples

kill two birds with one stone, do one task and finish two or more goals (literally, “one stone, two birds”)

(obsolete) being surprised twice / (obsolete) more specifically, describes the appearance of a woman who has a beautiful figure from behind but has an ugly face

(grammar) a verbal conjugation class in which the verb stem ends in -i and consists of four alternating bases: -i, -iru, -ire, and -iyo/-iro

Kyūjitai form of 三位一体 (“Trinity”)