The term BLACK PIANO KEY can be broken down into seven crossword solutions: EBONY (5 letters), EBON (4 letters), BFLAT (5 letters), DFLAT (5 letters), EFLAT (5 letters), GFLAT (5 letters), and SHARP (5 letters). EBONY and EBON refer to a black color, while BFLAT, DFLAT, EFLAT, GFLAT, and SHARP are musical notes that can be played on a piano. All of these notes are found on a black key on the piano, hence the term BLACK PIANO KEY.