an officer in the Roman army, being an assistant or lieutenant to every centurion. The optio was so called because he was the choice or option of the centurion in later times; at first, however, he had been chosen by the tribune, or chief commander of the legion. These optiones are also sometimes called fucceuturiones and tergiuductores; the last name was given them because their post was in the rear of the company. Some authors make mention of sub-optiones or sub-lieutenants.

It is proper, however, to add, that optiones were not peculiar to the camp, but were also used in a variety of other offices of life.