(; plural ; ) was a Roman imperial honorific title given to empresses and women of the imperial families. It was the feminine form of Augustus. In the third century, could also receive the titles of ("Mother of the Senate"), ("Mother of the Camp"), and ("Mother of the Fatherland").
The title implied the greatest prestige. could issue their own coinage, wear imperial regalia, and rule their own courts.
Agrippina, the wife of Claudius, was the first living wife of the emperor in Roman history to receive the title of , a position she held for the rest of her life, ruling with her husband and son.
In the third century, Julia Domna was the first empress to receive the combined title after the death of her husband Septimius Severus, which may have implied greater powers being vested in her than was usual for a Roman empress mother. In this official position and honor, she accompanied her son on an extensive military campaign and provincial tour.