harmony

Harmony is defined as agreement, or is defined as a mix of pleasing musical notes that go together.

(noun)

An example of harmony is when two people live together and don't fight.
An example of harmony is when two people sing contrasting parts of a duet that go together perfectly.

See harmony in Webster's New World College Dictionary

noun pl. harmonies

a combination of parts into a pleasing or orderly whole; congruity
agreement in feeling, action, ideas, interests, etc.; peaceable or friendly relations
a state of agreement or orderly arrangement according to color, size, shape, etc.
an arrangement of parallel passages of different authors, esp. of the Scriptures, so as to bring out corresponding ideas, qualities, etc.
agreeable sounds; music
Music
1. the simultaneous sounding of two or more tones, esp. when satisfying to the ear
2. structure in terms of the arrangement, modulation, etc. of chords
3. the study of this structure

Origin: ME armony < OFr harmonie < L harmonia < Gr < harmos, a fitting < IE base *ar- > art, arm

See harmony in American Heritage Dictionary 4

noun pl. har·mo·nies

Agreement in feeling or opinion; accord: live in harmony.
A pleasing combination of elements in a whole: color harmony; the order and harmony of the universe. See Synonyms at proportion.
Music
a. The study of the structure, progression, and relation of chords.
b. Simultaneous combination of notes in a chord.
c. The structure of a work or passage as considered from the point of view of its chordal characteristics and relationships.
d. A combination of sounds considered pleasing to the ear.
A collation of parallel passages, especially from the Gospels, with a commentary demonstrating their consonance and explaining their discrepancies.