D-flat minor
Minor key with eight flats, including one double flat; in practice almost always notated enharmonically as C-sharp minor.
What it means
D-flat minor is the minor key whose tonic is D♭, formed by transposing the minor key to that root. It is therefore the relative minor of F-flat major, a major key that is barely used in practice.
In the notation
In purely theoretical terms, D-flat minor requires eight accidentals, one of them a double flat, to represent the scale correctly. This many accidentals is unwieldy in practice, which is why D-flat minor is almost never actually notated this way.
Instead, the key is nearly always written enharmonically, meaning identical in sound but spelled differently, as C-sharp minor. C-sharp minor needs only four sharps and is therefore considerably easier to read and play.
Musical use
In scores, D-flat minor therefore appears almost exclusively in the form of its enharmonic counterpart, C-sharp minor. The theoretical name D-flat minor mainly retains importance for the systematics of the circle of fifths and for understanding enharmonic relationships, for instance when a modulation from the flat side is followed through consistently.