IPA: /ˈhɛərdəm/
KK: /ˈhɛrˌdəm/
The state or condition of being an heir, which means having the right to inherit property or titles from a family member.
After his father's death, he was in line for the heirdom of the family estate.
Heirdom is formed from "heir" (from Old French *eir*, meaning one who inherits) and "-dom" (meaning state or condition). The word refers to the state or condition of being an heir, or the rights and privileges associated with inheritance.
Think of an 'heir' as someone who inherits, and '-dom' indicating a state or condition — so heirdom means the state of being an heir.