What does "heir" mean?

Heir: One who receives any endowment from an ancestor or relation; as, the heir of one's reputation or virtues. And I his heir in misery alone. Pope. Heir apparent. (Law.) See under Apparent. -- Heir at law, one who, after his ancector's death, has a right to inherit all his intestate estate. Wharton (Law Dict.). -- Heir presumptive, one who, if the ancestor should die immediately, would be his heir, but whose right to the inheritance may be defeated by the birth of a nearer relative, or by some other contingency.