bassyoudaoicibaDictYouDict[bass 词源字典]
bass: Bass the fish [15] and bass the musical term [15] are of course completely unrelated words, with different pronunciations. Bass meaning ‘of the lowest register’ is simply a modified spelling of the adjective base, under the influence of Italian basso. Related words are bassoon [18], from French basson, and basset-horn [19], a partial translation of Italian corno di bassetto, literally ‘bass horn’.

The bass is a spiny-finned fish, and it may be that its name is related to Old English byrst ‘bristle’. The Old English term for the fish was bærs, which survived dialectally until the 19th century in the form barse, and it is thought that it goes back to a Germanic base *bars- (source of German barsch); this may be cognate with *bors-, from which Old English byrst came.

In the 15th century, barse underwent some sort of phonetic mutation to produce bass.
=> base, bassoon[bass etymology, bass origin, 英语词源]
bass (adj.)youdaoicibaDictYouDict
late 14c., of things, "low, not high," from Late Latin bassus "short, low" (see base (adj.)). Meaning "low in social scale or rank" is recorded from late 14c. Of voices and music notes, from mid-15c. (technically, ranging from the E flat below the bass stave to the F above it), infuenced by Italian basso. Meaning "lowest part of a harmonized musical composition" is from mid-15c. Meaning "bass-viol" is from 1702; that of "double-bass" is from 1927.
bass (n.)youdaoicibaDictYouDict
freshwater fish, c. 1400 corruption of Middle English baers, from Old English bærs "a fish, perch," from Proto-Germanic base *bars- "sharp" (cognates: Middle Dutch baerse, Middle High German bars, German Barsch "perch," German barsch "rough"), from PIE root *bhar- "point, bristle" (see bristle (n.)). The fish was so called for its dorsal fins. For loss of -r-, see ass (n.2).