heir heir /ˈɛr/

noun

1. () A person who is entitled by law or by the terms of a will to inherit the estate of another  ( heritor , inheritor , distributee [American] , heir )
   a person who is entitled by law or by the terms of a will to inherit the estate of another
     The young prince was the rightful heir to the throne.
   The young prince was the rightful heir to the throne.
   
2. A person who inherits some title or office  ( heir , successor )
   a person who inherits some title or office