harmonyyoudaoicibaDictYouDict
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.
axe (n.)youdaoicibaDictYouDict
Old English æces (Northumbrian acas) "axe, pickaxe, hatchet," later æx, from Proto-Germanic *akusjo (cognates: Old Saxon accus, Old Norse ex, Old Frisian axe, German Axt, Gothic aqizi), from PIE *agw(e)si- (cognates: Greek axine, Latin ascia).
The spelling ax is better on every ground, of etymology, phonology, and analogy, than axe, which became prevalent during the 19th century; but it is now disused in Britain. [OED]


The spelling ax, though "better on every ground, of etymology, phonology, & analogy" (OED), is so strange to 20th-c. eyes that it suggests pedantry & is unlikely to be restored. [Fowler]
Meaning "musical instrument" is 1955, originally jazz slang for the saxophone; rock slang for "guitar" dates to 1967. The axe in figurative sense of cutting of anything (expenses, workers, etc.), especially as a cost-saving measure, is from 1922, probably from the notion of the headman's literal axe (itself attested from mid-15c.). To have an axe to grind is from an 1815 essay by U.S. editor and politician Charles Miner (1780-1865) in which a man flatters a boy and gets him to do the chore of axe-grinding for him, then leaves without offering thanks or recompense. Misattributed to Benjamin Franklin in Weekley, OED print edition, and many other sources.
bifocals (n.)youdaoicibaDictYouDict
"bifocal spectacles," 1899, see bifocal. Conceived by Benjamin Franklin, but called by him double spectacles.
boozy (adj.)youdaoicibaDictYouDict
"inebriated," 1719, from booze + -y (2). It was one of Benjamin Franklin's 225 synonyms for "drunk" published in 1722. Related: Boozily; booziness.
FranklinyoudaoicibaDictYouDict
Middle English Frankeleyn, attested as a surname from late 12c., from Anglo-French fraunclein "freeholder, land-owner of free but not noble birth," from Old French franc "free" (see frank (adj.)); probably with the Germanic suffix also found in chamberlain.

The Franklin stove (1787) so called because it was invented by U.S. scientist/politician Benjamin Franklin (1706-1790). In early 19c., lightning rods often were called Franklins from his famous experiments with lightning in the 1750s.