What are cannibals?

Cannibals are humans who eat other humans.

Or: Species that consume for food their same species: MANY animals have been known to exhibit cannibalistic behaviors.
1)a person who eats the flesh of another person "cannibal tribes"
2)an animal that feeds on flesh of it's own species
Someone who eats people. An animal that feeds on others of its own kind.
Popular definition is that Cannibal means a species that eats members of its own species. Historically Cannibal is a named used to describe a set of Caribbean islanders (the Carib tribe) that waged war on the Spanish Armada. One of their tactics was to sneak on board, or otherwise ambush the armada and steal the body parts of victims. These body parts would be displayed on pikes around islands that this group claimed as a warning to others. While the 'act' generally ascribed to the term is older than this tribe or conflict, it was during this conflict that the term was linked to the act.
to eat something of your own species, in most cases, for a human to kill and eat another human.