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, "low in tone" from mid-15c. (technically, ranging from the E flat below the bass stave to the F above it), infuenced by Italian basso.
freshwater fish, c. 1400 corruption of Middle English baers, from Old English bærs "a fish, perch," from Proto-Germanic base *bars- "sharp" (source also of 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).
"lowest part of a harmonized musical composition," c.1500, from bass (adj.) or cognate noun in Italian. Meaning "singer having a bass voice" is from 1590s. Meaning "bass-viol" is from 1702; that of "double-bass" is from 1927.