kitchen maid, a drudge" (mid-15c.; hard pieces in a bread loaf from imperfect kneading were called 'slut's pennies
, 18c.). Meaning "woman of loose character, bold hussy" is attested from mid-15c.; playful use of the word, without implication of loose morals, is attested from 1660s.
"Our little girl Susan is a most admirable slut, and pleases us mightily." [Pepys, diary, Feb. 21, 1664]
Sometimes used 19c. as a euphemism for bitch to describe a female dog. There is a group of North Sea Gmc. words in sl- that mean "sloppy," and also "slovenly woman," and that tend to evolve toward "woman of loose morals" (cf. slattern
, also English dial. slummock "a dirty, untidy, or slovenly person," 1861; M.Du. slore "a sluttish woman").