harmonyyoudaoicibaDictYouDict[harmony 词源字典]
harmony: [14] The etymological idea behind harmony is ‘fitting things together’ – that is, of combining notes in an aesthetically pleasing manner. It comes via Old French harmonie and Latin harmonia from Greek harmoníā ‘means of joining’, hence ‘agreement, concord’, a derivative of harmós ‘joint’. As a musical term in Greek it appears to have denoted ‘scale’, or more simply just ‘music’, and its original use in English was for what we would now call ‘melody’.

It was not applied to the combination of notes to form chords (a practice which originated in the 9th century) until the 16th century. The term harmonica was coined in 1762 by the American physicist and statesman Benjamin Franklin for a musical instrument consisting of a set of water-filled glasses tuned to different notes and played with the fingers. It was first applied to the mouth-organ in the 19th century.
[harmony etymology, harmony origin, 英语词源]
harmonic (adj.)youdaoicibaDictYouDict
1560s, "relating to music," from Latin harmonicus, from Greek harmonikos "harmonic, musical, skilled in music," from harmonia (see harmony). From 1660s as "tuneful, harmonious; relating to harmony" (earlier as armonical "tuneful, harmonious," c. 1500). The noun, short for harmionic tone, is recorded from 1777. Related: Harmonically.
harmonium (n.)youdaoicibaDictYouDict
keyboard instrument, a kind of reed-organ popular late 19c. in homes and smaller churches, 1847, from French harmonium, from Greek harmonia (see harmony). Harmonium-like instruments predate the improved version patented 1840 in France by Alexandre Debain, who gave it the name.
harmony (n.)youdaoicibaDictYouDict
late 14c., "combination of tones pleasing to the ear," from Old French harmonie, 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)). Modern scientific harmony, using combinations of notes to form chords, is from 16c. Sense of "agreement of feeling, concord" is from late 14c.