The most notable may have been the two Pacidii who were commanders in the army of Gnaeus Pompeius Magnus during the Civil War.
[1] The nomen Pacidius belongs to a class of gentilicia formed from other names, using the suffix -idius.
[2] The root of the nomen is probably the Oscan praenomen Paccius, which was also used as a gentile name.
However, in at least some cases it is likely that Pacidius is instead an orthographic variation of Placidius, derived from the Latin cognomen Placidus, "peaceful".
[2] Despite the relatively small number of Pacidii known, it seems that they favoured the praenomina Publius and Gaius, and perhaps also Lucius, three of the most common names throughout Roman history.