Everyone knows what a pig is.

The pig (Sus domesticus), also called swine (pl.: swine) or hog, is an omnivorous, domesticated, even-toed, hoofed mammal. It is named the domestic pig when distinguishing it from other members of the genus Sus. Some authorities consider it a subspecies of Sus scrofa (the wild boar or Eurasian boar); other authorities consider it a distinct species.