A centurion (Latin: centurio; Greek: hekatontarchos) was a professional officer of the Roman army. In the Roman infantry, centurions commanded a centuria (century) of between 60 and 160 men, depending on force strength and whether or not the unit was part of the First Cohort. In the Roman legions tactical organization, the centurions ranked above the optios and below the Tribuni Angusticlavii - the aristocratic senior officers of the Equestrian Class, subordinate to the legion commander, the Legatus Legionis.