• (a.) Producing mathematically perfect harmony or concord; sweetly or perfectly harmonious.
Eu`har·mon'ic adjective [ Prefix -eu + harmonic .] (Mus.) Producing mathematically perfect harmony or concord; sweetly or perfectly harmonious. 
In music, euharmonic describes something producing a mathematically perfect harmony or concord. The term also describes a piece which is sweetly or perfectly harmonious.
euharmonic 1. Producing mathematically perfect harmony or concord; sweetly or perfectly harmonious. 2. Producing harmony or concordant sounds; as the euharmonic organ.