Definition of "nightly"

nightly¹

/ˈnaɪtli/

adjective
not comparable
1. Happening or appearing in the night; night-time; nocturnal.
  Quotations
  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.
3. Used in the night.

nightly²

/ˈnaɪtli/

adverb
not comparable
1. Every night.
  Quotations
  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
plural nightlies
1. (computing) A build of a software program with the latest changes, released every night.
  Quotations
  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