Paterfamilias is the Latin term for 'the father of the family' or 'the owner of the family estate'.
It was the oldest living male in the household who held the authority over the whole family. This included also his extended relatives, slaves and freedmen. He also held legal privilege over the property of the family.
He had a duty to father and raise healthy children as future citizens. He was held responsible for maintaining the well-being of his family and his property and to serve in Rom's political, religious and social life.