What is "optio"

An optio (plural optiones; , from optāre, "to choose", because an optio was chosen by his centurion), sometimes anglicized option (though rarely, to avoid confusion with "option"), was a soldier in the Roman army who held a position similar to that of a company's executive officer in modern armies. The optio seems to have held a rank roughly equivalent to that of a modern lieutenant, reflective of his status as the second in command of the century in which he served. The main function of an optio was as an optio centuriae, the second-in-command of a century, although there were many other positions an optio could hold.

Optiones were vital units in the Roman army. An optio was stationed at the rear of the ranks to keep the troops in order. Their duties would include enforcing the orders of the centurion, taking over the centurion's command in battle should the need arise, supervising his subordinates, and a variety of administration duties.

Optio pay was double the standard legionary pay and they were the most likely men to replace the centurion if the position became vacant.