Harmony

[hahr-muh-nee] /ˈhɑr mə ni/

noun, plural harmonies.
1.
agreement; accord; harmonious relations.
2.
a consistent, orderly, or pleasing arrangement of parts; congruity.
3.
Music.

4.
an arrangement of the contents of the Gospels, either of all four or of the first three, designed to show their parallelism, mutual relations, and differences.
/ˈhɑːmənɪ/
noun (pl) -nies
1.
agreement in action, opinion, feeling, etc; accord
2.
order or congruity of parts to their whole or to one another
3.
agreeable sounds
4.
(music)

5.
a collation of the material of parallel narratives, esp of the four Gospels
n.

late 14c., from Old French armonie “harmony,” also the name of a musical instrument (12c.), from Latin harmonia, from Greek harmonia “agreement, concord of sounds,” also as a proper name, the personification of music, literally “means of joining,” used of ship-planks, etc., also “settled government, order,” related to harmos “fastenings of a door; shoulder,” from PIE *ar-ti-, from *ar- “to fit together” (see arm (n.1)). Musical sense is oldest in English; that of “agreement of feeling, concord” is from late 14c.

The sounding of two or more musical notes at the same time in a way that is pleasant or desired. Harmony, melody, and rhythm are elements of music.