enharmonic

adjective Music.

having the same pitch in the tempered scale but written in different notation, as G sharp and A flat.

adjective music

denoting or relating to a small difference in pitch between two notes such as A flat and G sharp: not present in instruments of equal temperament such as the piano, but significant in the intonation of stringed and wind instruments
denoting or relating to enharmonic modulation

adj.

c.1600, from Late Latin enharmonicus, from Greek enharmonikos, from en (see en- (2)) + harmonikos (see harmonic).