Petillia gens

[1] The nomen Petillius, also spelled Petilius, Petelius, and Petellius, is almost certainly derived from the cognomen Petilus, meaning "slender", and belongs to a class of gentilicia formed using the typically diminutive suffixes -illius and -ellius.

[2] The name is regularly confused with that of the Poetelii, an older plebeian family that occurs from the time of the Decemvirs down to the period of the Samnite Wars, but they do not appear to have been the same.

[1] The only surnames of the Petillii in the time of the Republic were Capitolinus and Spurinus, of which only the former occurs on coins.

Although Deecke noted the use of the praenomen Spurie by the Etruscans, the orthography used in Greek transliterations argued in favour of a Latin origin.

[4] The cognomen Capitolinus is said to have been bestowed upon one of the Petillii who was caretaker of the Temple of Jupiter on the Capitoline Hill in the time of Augustus.