harmony

Etymology

First attested in 1602. From Middle English armonye, from Old French harmonie/armonie, from Latin harmonia, from Ancient Greek ἁρμονία (harmonía, “joint, union, agreement, concord of sounds”), either from or cognate with ἁρμόζω (harmózō, “I fit together”), from Proto-Indo-European *h₂er- (“to join, fit, fix together”).

noun

1. Agreement or accord.
   December 4 2010, Evan Thomas, "Why It’s Time to Worry", in Newsweekk America's social harmony has depended at least to some degree on economic growth. It is easier to get along when everyone, more or less, is getting ahead.
2. A pleasing combination of elements, or arrangement of sounds.
3. (music) The academic study of chords.
4. (music) Two or more notes played simultaneously to produce a chord.
5. (music) The relationship between two distinct musical pitches (musical pitches being frequencies of vibration which produce audible sound) played simultaneously.
   I did not know anything more about music,only about finger exercises, difficult tasks, contradictions in the theory of harmony, and tedious piano lessons from a sarcastic teacher who saw in my […] 2012-12-21, Hermann Hesse, Gertrude: A Novel, Farrar, Straus and Giroux, →OCLC
6. A literary work which brings together or arranges systematically parallel passages of historians respecting the same events, and shows their agreement or consistency.
   a harmony of the Gospels