Core:

A core is a hero or role that is expected to earn gold and experience efficiently and turn that farm into team damage, pressure, or late-game impact. In Dota 2, cores usually occupy the safe lane, mid lane, or off lane and are prioritized for resources so they can become strong enough to lead fights and take objectives.

The term is used to distinguish these heroes from supports, who generally take a lower-resource role and provide vision, control, and assistance.