1510s, "low, base, lewd," later "untidy, dirty" (1560s), from sloven + -ly (1). Related: Slovenliness; also in this sense was slovenry (1540s), which OED reports in common use early 17c.
slovenly appearance
slouchy
slough
Slovak
sloven
Slovene
slovenly
slow
slowdown
slowly
slowness
slowpoke
