Primogeniture

n. right of the firstborn child or eldest son to receive the family inheritance

Primogeniture is the common law right of the first born son to inherit the entire estate, to the exclusion of younger siblings. It is the tradition of inheritance by the first-born of the entirety of a parent's wealth, estate or office; or in the absence of children, by collateral relatives, in order of seniority of the collateral line.
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Noun
1. right of inheritance belongs exclusively to the eldest son
(hypernym) inheritance, heritage

n. primogeniture, right of the firstborn child or eldest son to receive the family inheritance

n. primogeniture, birthright