A centurion (Latin: centurio; Ancient Greek: κεντυρίων), also hekatontarch (ἑκατόνταρχος, hekatontarchos) in Greek sources, or, in middle Byzantine times, kentarch (κένταρχος, kentarchos), was a professional officer of the Roman army after the Marian reforms of 107 B.C. Most centurions commanded 80 men but senior centurions commanded cohorts, or took senior staff roles in their legion. Centurions were also found in the Roman navy. Centuries, or Centuriae, means tribe or company. Theoretically, this word traces its roots to centum which is Latin for one hundred, but that connection is widely disputed or disregarded.