"overseer," 1640s, American English, from Dutch baas "a master," Middle Dutch baes, of obscure origin. If original sense was "uncle," perhaps it is related to Old High German basa "aunt," but some sources discount this theory. The Dutch form baas is attested in English from 1620s as the standard title of a Dutch ship's captain. The word's popularity in U.S. may reflect egalitarian avoidance of master (n.) as well as the need to distinguish slave from free labor. The slang adjective meaning "excellent" is recorded in 1880s, revived, apparently independently, in teen and jazz slang in 1950s.
"protuberance, button," c.1300, from Old French boce "a hump, swelling, tumor" (12c., Modern French bosse), from either Frankish *botija or Vulgar Latin *bottia, both of uncertain origin.
1856, from boss (n.1). Related: Bossed; bossing.
A circumscribed rounded swelling; a protuberance.
The prominence of a kyphosis or humpback.
Excellent; wonderful; the MOST •This old use seems to have been revived independently by 1950s jazz musicians and teenagers: Aw, this is boss/ Japan has leaped into the implements-for-bosser-living gap (1880s+)
: That little guy bosses the whole operation (1850s+)
[fr Dutch baas, ''master'']