Meaning

noun an incompetent person; usually used in negative constructions

noun a stooping carriage in standing and walking

verb assume a drooping posture or carriage

originUnclear. Perhaps from Middle English slugge, from Old Norse slókr (“lazy fellow”). See also Swedish sloka (“to slouch, wilt”), related to Swedish slak (“slack, soft and flexible”) and Latin laxus (“loose, slack”).

Etymology from Wiktionary, CC BY-SA 3.0