an·ces·tor [án sèst?r, áns?st?r] (plural an·ces·tors) noun 1. distant relation somebody is descended from: somebody from whom somebody else is directly descended, especially somebody more distant than a grandparent 2. forerunner: a predecessor of somebody, e.g. in the development of an art form 3. biology earlier species: an animal or plant from which a species has evolved 4. earlier model: a device that was an earlier form of a modern invention or was used as a basis for developing it [14th century. Via Old French ancestre < Latin antecessor "somebody who goes before" < cess-, past participle of cedere "give way"]