ENHARMONIC, a musical term having more than one meaning. In its earliest use it was applied to one of the three gen era in ancient Greek music, viz., thy diatonic, the chromatic and the enharmonic, the last-named containing intervals smaller than a semitone, termed dieses. In modern usage it is employed in such terms as "enharmonic modulation," "enharmonic notation," and the like, when, in consequence of the adoption of equal tempera ment, what are actually two different notes, e.g., C sharp and D flat, are treated as one and the same. Thus in the following ex ample, illustrating how a chord can be enharmonically altered, the notes as actually sounded on the pianoforte are the same in each instance, but in consequence of the altered notation each chord is, harmonically considered, entirely different and belongs to a differ ent key : To which it should be added that an enharmonic change of nota tion may also be adopted for simple convenience of performance (i.e., to avoid a multiplicity of sharps or flats) and without any modulatory purpose. (See HARMONY ; MODULATION.)