slob n.

1780, "mud, muddy land," from Irish slab "mud, mire dirt," itself probably borrowed from English slab "muddy place" (c. 1600), from a Scandinavian source (compare Icelandic slabb "sludge"). The meaning "untidy person," often with implications of "dull, slow, loutish, easily imposed upon," emerged by 1887, probably shortened from earlier expressions such as slob of a man (1861).