The term 'inheritor under primogeniture' refers to the ELDEST child in a family who is legally entitled to inherit the entirety of their parent's estate. Primogeniture is a system of inheritance where the ELDEST child has the right to inherit all of their parent's property, regardless of gender. This system was historically used in many countries, including England and France, and is still used in some parts of the world today. The term 'ELDEST' is used to refer to the first-born child in a family, and is typically used in the context of primogeniture.