nightly

Etymology 1

From Middle English nyȝtly, nihtlich, nihtlic, from Old English nihtlīċ, nihtelīċ (“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”).

adj

1. Happening or appearing in the night; night-time; nocturnal.
   nightly dews
   A cobweb spread above a blossom Is sufficient to protect It from nightly chill. 1871, John Tyndall, Fragments of Science: A Series of Detached Essays, Lectures, and Reviews
2. Performing, occurring, or taking place every night.
   The dog demanded to go out for his nightly walk.
3. Used in the night.

Etymology 2

From Middle English nyghtly, neghtly, from Old English *nihtlīċe (“nightly”), equivalent to night + -ly.

adv

1. Every night.
   He checks his email nightly.
   I practice nightly, I try to keep ahead / This art of surfacing is all but dead 1979, The Boomtown Rats (lyrics and music), “Wind Chill Factor (Minus Zero)”, in The Fine Art of Surfacing

noun

1. (computing) A build of a software program with the latest changes, released every night.
   Depending on how brave you are, you can even set it to update to the “bleeding edge nightlies” instead of just the point release nightlies if you want to really see the cutting edge of WordPress core development. 2014, Adam Onishi, Pro WordPress Theme Development, Apress, page 349