slovenly adj.

late 15c., slovein, "person of low character; rascal, knave" (regardless of gender); probably from a continental Germanic source, compare Middle Flemish sloovin "a scold," sloef "untidy, shabby," Dutch slof "careless, negligent," Middle Low German sloven "put on clothes carelessly," from Proto-Germanic *slaubjan, from PIE root *sleubh- "to slide, slip."

The meaning "person careless of dress or negligent of cleanliness" in English is by 1520s. The older "knave" sense is obsolete. The earliest appearance of the English word is in the Coventry mystery plays (paired alliteratively with slut) amid a volley of insults hurled by scribes and Pharisees against the woman taken in adultery, so its earliest sense sometimes is given as "immoral woman."

Century Dictionary also compares Low German sluf "slovenly," sluffen, sluffern "be careless," sluffen "go about in slippers;" German schlumpe "a slut, slattern," schlumpen "draggle."

Sloven is given in the older grammars as the masculine correlative of slut; but the words have no connection, and the relation, such as it is, is accidental. Slut, as now used, is much stronger and more offensive. [Century Dictionary, 1895]

suffix forming adjectives from nouns and meaning "having qualities of, of the form or nature of" (manly, lordly), "appropriate to, fitting, suited to" (bodily, earthly, daily); irregularly descended from Old English -lic, from Proto-Germanic *-liko- (Old Frisian -lik, Dutch -lijk, Old High German -lih, German -lich, Old Norse -ligr), related to *likom- "appearance, form" (Old English lich "corpse, body;" see lich, which is a cognate; see also like (adj.), with which it is identical).