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

(collective, literally) a thousand nights / (archaic, figuratively, collective) lots of nights; an innumerable number of nights

a female given name

Short for 十六夜の月 (izayoi no tsuki): the moon just past the full moon, the start of the waning moon

the sixteenth night of the month under the lunar calendar, just after the full moon

Nymphaea lotus, the white Egyptian lotus

Compounds

(archaic, literary) to sleep with clothes overturned, as to meet their longed-for partner in a dream