Decimus (/ˈdɛsɪməs/ DESS-im-əs, Classical Latin: [ˈdɛkɪmʊs]), very rarely feminine Decima, is a Latin praenomen, or personal name, usually abbreviated D. Although never especially common, Decimus was used throughout Roman history from the earliest times to the end of the Western Empire and beyond, surviving into modern times.
[2][3] Decimus was especially favored by the plebeian gens Junia, which may originally have been patrician.
[2] Decimus is the Latin word for tenth, and it falls into a class of similar praenomina including the masculine names Quintus, Sextus, Septimus, Octavius, and Nonus, as well as the feminine names Prima, Secunda, Tertia, Quarta, Quinta, Sexta, Septima, Octavia, and Nona.
However, it has also been argued that Decimus and the other praenomina of this type could refer to the month of the year in which a child was born.
[4][2] The Oscan praenomen Decius or Deciis is derived from the same root, and gave rise to the patronymic gens Decia.