Julia (Classical Latin: Iulia) is the nomen of various women of the family Julii Caesares, a branch of the gens Julia, one of the most ancient patrician houses at ancient Rome.
By the time of the later Republic, Roman daughters were seldom given personal names, or praenomina, unless there were several sisters in a family, and were instead known by a variety of less formal names when it became necessary to distinguish between them. A first daughter might simply continue to be known by her nomen alone, especially if she were much older than her sisters, or she might become known as Julia Major ("the elder"), Julia Maxima ("the eldest"), or Julia Prima ("the first"). Younger daughters might become known as Julia Minor ("the younger"), Julia Secunda ("the second"), Julia Tertia ("the third"), Julia Paulla ("little Julia"), and so forth.
Outside the family, some women became known by a combination of their father's nomen and cognomen; the daughter of Lucius Julius Severus would be referred to as Julia Severa in order to distinguish her from other women named Julia. But because many names were very common, this was often insufficient to distinguish among individuals. Often women were identified by reference to their fathers or husbands. Julia, the daughter of Sextus Julius Caesar, might be identified as Julia Caesaris filia ("Julia, daughter of Caesar"). This particular nomenclature has led to the mistaken belief that Caesaris and similar names are the women's surnames, although in fact they are merely the genitive forms of masculine names, and refer to other people. Care must be taken to distinguish between these names and women's cognomina.