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.
freshwater fish, early 15c. corruption of Old English bærs "a fish, perch," from Proto-Germanic base *bars- "sharp" (cf. 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-, cf. ass (n.2).