bass (adj.)

late 14c., "low, of little height," from Old French bas "low, lowly, mean," from Late Latin bassus "thick, stumpy, low" (used only as a cognomen in classical Latin, humilis being there the usual word for "low in stature or position"), which is of uncertain origin, possibly from Oscan, or Celtic, or related to Greek basson, comparative of bathys "deep."

The meaning "low on the social scale" is from late 15c.; that of "low in the moral scale" is attested by 1530s in English. The meaning "befitting an inferior person or thing, unworthy" is from 1590s. Base metals (c. 1600) were worthless in contrast to noble or precious metals. Related: Basely.

"stiff, coarse hair of certain animals," especially those set along the backs of hogs, Old English byrst "bristle," with metathesis of -r-, from Proto-Germanic *bursti- (source also of Middle Dutch borstel, German borste, Danish börste), from PIE *bhrsti- from root *bhars- "point, bristle" (source also of Sanskrit bhrstih "point, spike"). With -el, diminutive suffix. Extended to similar appendages on some plants and insects.