ala (pi. alae): A contingent supplied for the army by Rome’s Italian allies. It had roughly the same number of infantry as a legion, but two to three times as many cavalry.
centurion: The commander of a century in a Roman legion. Some of these men were elected, others appointed to the post.
century: The basic administrative sub-unit of the Roman legion. Each contained from thirty to eighty men and was led by a centurion. There were sixty centuries in each legion.
cohort: The most important sub-unit of an ala. The size and internal organization of the cohort are unknown.
consul: Rome's most senior magistrates were the two consuls who held office for a year beginning in March. The consuls were allocated all the most important tasks required by the Republic.
decurion: The commander of a file of ten Roman cavalrymen. There were three decu- rions in each turma.
dictator: In times of crisis the Roman Republic could choose to appoint a single magistrate, or dictator, with supreme power. His term of office was set at six months and could not be renewed.
equites: The highest social and economic class in Roman society, the eqnites, or ’knights', provided the cavalry of the legions.
hastatus ( pi. hastati): The first line of heavy infantry in the legion, recruited from the younger men.
legion: The most important unit in the Roman army, a legion consisted of cavalry, light infantry, and three lines of close order infantry. There were at least 4,000 foot and 200 horse in each legion, but this number was often increased.
Magister Equitum: The second in command to a dictator.
maniple: The basic tactical unit of the heavy infantry in a legion consisted of two
centuries. It was commanded by the centurion of the right-hand maniple if both centurions were present. There were ten maniples in each of the three lines.
optio (pl. optiones): The centurion’s second in command, the optio traditionally stood at the rear of the century.
pilum (pl. pila): The heavy javelin which equipped the hastati and principes.
praetor: The four praetors elected each year were junior to the consuls and held less important military commands, as well as exercising judicial authority.
prefect: Three prefects commanded each ala. Their role was probably similar to that of the tribunes in a legion.
princeps (pi. principes): The second line of close order infantry in a Roman legion were recruited from men in the prime of life.
quaestor: Junior magistrates who oversaw the Republic's finances and acted as second in command to the consuls.
scutum (pl. scuta): A shield, especially the heavy oval body shield carried by Roman legionaries.
socii: The Latin and Italian allies of the Roman Republic. All were obliged to provide men or other support for Roman armies.
suffes (pl. suffetes): The two suffetes were the senior magistrates of the Carthaginian Republic. However, unlike the Roman consuls, they did not hold military commands. Hannibal was elected suffes after the Second Punic War.
triarius (pl. triaril): The infantry of the third line of a Roman legion, drawn from the oldest and most experienced soldiers.
tribune: The six tribunes were the senior officers of the legion. Command was held by a pair of tribunes in turn.
turma: The basic tactical unit of the Roman cavalry. It consisted of thirty men, including three decurions.
veles (pi. velites): The light infantry of the Roman legion, recruited from the poorest citizens and those too young to serve with the hastati.