[1] Members of the Mamilia gens afterward came to Rome, and the name must have been used by the ancestors of the Octavii and perhaps the Otacilii, but examples of the praenomen are scarce.
It might be expected to appear as Octavus, feminine Octava, but in the few examples known it seems to have been treated as an "-i stem", and is given as Octavius or Octavia.
This occurs with certain other praenomina, including the feminine forms Marcia and Titia, which are usually found in place of the expected Marca and Tita.
[6] Octavius falls into the same class as the masculine praenomina Quintus, Sextus, Septimus, Nonus, and Decimus, as well as the feminine names Prima, Secunda, Tertia, Quarta, Quinta, Sexta, Septima, Nona, and Decima.
[7] However, scholars have long postulated that, at least at Rome, such names might instead refer to the month of the year in which a child was born.