Black's Law Dictionary (2nd edition)dictionaries

Prsnomen

Lat. Forename, or first name. The first of the three names by which the Romans were commonly distinguished. It marked the individual, and was commonly written with one letter; as “A.” for “Au-lus;” “C.” for “Caius,” etc. Adams, Rom. Ant 35

Source: Black’s Law Dictionary 2nd Ed (1910)