Real Dictionary

enharmonic in American English
in equal temperament, designating or of tones, as C and D, that are identical in pitch but are written differently according to the key in which each occurs: enharmonic tones are especially important in instruments of fixed pitch, as the piano
adjective: having the same pitch in the tempered scale but written in different notation, as G sharp and A flat

enharmonic in British English
adjective: 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