This gens is known almost entirely from inscriptions, as none of its members held any of the higher offices of the Roman state.
The nomen Secundius is derived from the cognomen Secundus, originally indicating a second child.
[1] The main praenomina of the Secundii were Gaius, Marcus, Lucius, and Titus, all of which were amongst the most common names throughout all periods of Roman history.
There is no indication that the Secundii were ever divided into distinct families, and they used a wide variety of surnames under the Empire.
[2] Quadratus, while resembling the numerical cognomen quartus, actually described someone with a square or stocky figure.