This is the common Greek word for a female pig or sow. In Jewish law, pigs were quintessentially unclean animals, forbidden as food and symbolizing defilement. In 2 Peter 2:22, the sow appears in a proverb warning about apostates: like 'a sow that is washed' returning to wallow in mud, false teachers return to the pollution they seemed to have escaped. The image emphasizes innate nature—the sow's cleanliness was only external and temporary.