It is the inharmonious intraspecific relationship between individuals of the same species when they compete for the same environmental factors, especially space and food.
This relationship determines the density of the populations involved.
Cannibal is the individual who kills and eats another of the same species. Occurs with scorpions, spiders, fish, planarians, rodents, etc.
In the human species, when it exists, it is called anthropophagy (from the Greek anthropos, man; phagein, eat).