What is Patria Potestas?

Legal Definition
Civil law. Paternal power; (q. v.) the authority which is lawfully exercised by the father over his children.
-- Bouviers Law Dictionary
Legal Definition
Lafc In Roman law. Paternal authority; the paternal power. This term denotes the aggregate of those peculiar powers and rights which, by the civil law of Rome, belonged to the head of a family in respect to his wife, children, (natural or adopted,) and any more remote de-scondants who sprang from him through males only. Anciently, it was of very extensive reach, embracing even the power of Ilfe and death, but was gradually curtailed, until finally it amounted to little more than a right in the paterfamilias to hold as his own any property or acquisitions of one under his power. Mackeld. Rom. Law, ยง 589.
-- Black's Law Dictionary
Legal Definition
Paternal power.
-- Ballentine's Law Dictionary