Although the ultimate origin of "slut" is unknown, it first appeared in Middle English (1402) as slutte (AHD), with the meaning "a dirty, untidy, or slovenly woman." Even earlier, Geoffrey Chaucer used the word "sluttish" (c.1386) to describe a slovenly man; however, later uses appear almost exclusively associated with women. The modern sense of "a sexually promiscuous woman" dates to at least 1450.
Another early meaning was "kitchen maid or drudge" (c. 1450), a meaning retained as late as the 18th century, when hard knots of dough found in bread were referred to as "slut's pennies." A notable example of this use is Samuel Pepys's diary description of his servant girl as "an admirable slut" who "pleases us mightily, doing more service than both the others and deserves wages better" (February 1664). In the 19th century, the word was used as a euphemism in place of bitch in the sense of "a female dog."
Similar words appear in Dutch, German and Swedish dialects meaning "a dirty woman," indicating a common ancestor in Germanic languages. A popular theory connects "slut" to earlier Germanic forms meaning "slush" or "mud puddle," but this derivation remains in question.[1] Please note that the word "slut" used in modern Swedish (and pronounced differently than in English) means "ending".