noun

1. 1. the period from sunset to sunrise
   2. the period of actual darkness after sunset and before sunrise; also, a part of this period before bedtime [a night at the opera] or the part between bedtime and morning [a sleepless night]
2. the evening following a specified day Christmas night
3. the darkness of night
4. any period or condition of darkness or gloom; specif.,
   1. a period of intellectual or moral degeneration
   2. a time of grief
   3. death

Etymology: ME niht < OE, akin to Ger nacht < IE base *nekwt-, *nokwt- > Gr nyx (gen. nyktos), L nox (gen. noctis), night

adjective

1. of, for, or at night
2. active, working, or in use at night