Centurion was a military rank, common in many cultures.
The rank was used by the ancient Romans on Earth. Roman centurions would occasionally be put in charge of patrolling the various Roman provinces. In 2369, Richard Galen compared Jean-Luc Picard, who was on a survey mission, to a Roman centurion patrolling for the Empire. (TNG: "The Chase")
The Romulan Star Empire also used the rank of centurion. A crew member of the Romulan Bird-of-Prey that destroyed several Earth outposts along the Earth-Romulan Neutral Zone in 2266 was a centurion. (TOS: "Balance of Terror")