Roman first name (ThlL, Onom. 3,73-76), probably did not indicate the place in a sequence (‘the tenth’) of births but the month of the birth; abbreviated D., in the Imperial period also Dec.; Greek Δέκμος, later Δέκιμος. The name was not used by patrician families and is otherwise rare as well (more frequent among the Iunii ( Iunius) Bruti and the Laelii ( Laelius)); in the Imperial period, it is also documented as a cognomen (for example with Aurelius, Flavius, Pacarius) and as a nomen.
Kajanto, Cognomina, 172
Salomies, 27f., …