Webster's Revised Unabridged Dictionary · 1913

Birthright

Birthright ({not transcribed}) , noun

Any right, privilege, or possession to which a person is entitled by birth, such as an estate descendible by law to an heir, or civil liberty under a free constitution; esp. the rights or inheritance of the first born.
Lest there be any... profane person, as Esau, who for one morsel of meat sold his birthright. — Heb. xii. 16