D-flat major

Short definition from Wiktionary

Noun

1. 1
   A major key with the notes D♭, E♭, F, G♭, A♭, B♭, C, the key signature of which has five flats.
2. 2
   The major chord with the notes D♭, F, and A♭.

Adjective

1. 1
   Describing a piece, song, or scale that has a D-flat major key.