- Obsolete of, like, or characteristic of the night
- done or occurring every night
- Obsolete at night
- night after night; every night
- Of or occurring during the night; nocturnal: the cat's nightly prowl.
- Happening or done every night: the physician's nightly rounds.
- Every night.
- He checks his email nightly.
From Middle English *nightly, nyȝtly, nihtlich, from Old English nihtlīc, nihtelīc (“nocturnal, nightly, of the night, at night”), equivalent to night + -ly. Cognate with Scots nichtlie (“nightly”), West Frisian nachtlik (“nightly, nocturnal”), Dutch nachtelijk (“nightly, nocturnal”), German nächtlich (“nocturnal, nightly”), Danish natlig (“nightly”), Swedish nattlig (“nightly, nocturnal”).