What is Alieni Juris?

Legal Definition
Lat. Under the control or subject to the authority, of another person; e. g., an infant who is under the authority of his father or guardian; a wife under the power of her husband. The term is centrasted with Sui Juris, (q. v.)
-- Black's Law Dictionary
Legal Definition
Under another’s control as distinguished from sui juris.
-- Ballentine's Law Dictionary