From Middle English pork, porc, via Anglo-Norman, from Old French porc ("swine, hog, pig; pork"), from Latin porcus ("domestic hog, pig"), from Proto-Indo-European *pórḱos ("piglet"). Cognate with Old English fearh ("piglet"). More at farrow.
Used in English since the 14th century, and as a term of abuse since the 17th century.