ala: (a) In the Mid Republican period an ala of allies was normally attached to support each legion of Roman citizens. It consisted of roughly the same number of infantry, but as many as three times the number of cavalry.
(b) In the professional army, an ala was a unit of auxiliary cavalry roughly equivalent in size to an infantry cohort.
aquila: The silver, later gold or gilded eagle which became the most important standard of the legion after Marius, who was elected consul in 107 вс.
aquilifer. The standard-bearer who carried the aquila (eagle) standard of the legion.
beneficiarius: Experienced soldier attached to the staff of a provincial governor. They often performed policing functions and were detached as individuals or small groups.
caliga (pi. caligae): The hob-nailed military boot worn by soldiers. By the 2nd century AD these were often replaced by enclosed boots.
canabae: The civilian settlement that grew up very quickly around virtually every permanent or semi permanent base established by the Roman army.
capile censi: The ‘head count’ (also known as proletarii) of citizens who lacked sufficient property to qualify them for military service and so were listed simply as numbers in the census. Marius openly recruited volunteers from this class.
century (centuria): Basic administrative unit of the Republican and early imperial army, which ranged in size from 30 to 160 men, depending on period and unit, but on average had a ‘paper’ strength of 80.
centurion (centurio): Officer commanding a century.
cohort (cohors): A unit of some 400-800 men, the cohort was the basic tactical unit of the professional army.
cohors equitata: A 'mixed' cohort consisting of both auxiliary infantry and cavalry. Horsemen in these units were not as well paid as the cavalrymen of the alae.
comes: Late Roman senior officer in one of the field armies.
comitatenses: The units of the field armies at the immediate disposal of the emperors or their commanders in the 4th and 5th centuries ad.
contubemium: Term applied to the group of eight men who shared a tent and messed together.
comicularius: Clerk on the staff of a unit officer or provincial governor.
corvus: The ‘raven’, a type of boarding-bridge fitted to each Roman vessel, devised and used with great success by the Romans during the First Punic War.
cuneus: Title given to some cavalry units in the army of Late Antiquity.
decurion (decurio): Cavalry officer originally in command of a group of 10 men. By the Principate a decurion commanded a turma or about 30 men.
dictator. At times of extreme military crisis, the Republic appointed a dictator, a single magistrate with supreme power who held office for six months. The appointment of a dictator was extremely rare. However, during the 1st century вс, men like Sulla and Caesar seized power by force and employed the title.
dilectus: The levy by which the Republic recruited its armies. It is unclear how such levies were held from the 1st century BC onwards.
duplicarius: Soldier receiving double pay and probably acting as a junior officer.
dux: Senior officer in the Late Roman army, commanding a region and its garrison of limitanei.
equites: The ‘Knights’ were originally the citizens wealthy enough to equip themselves as cavalrymen in the militia army. The name was adopted by the social class immediately below the senatorial class.
foederati: Initially simply an irregular unit of auxiliaries, in Late Antiquity the term was used to describe allied troops serving under their own leaders.
funditores: Slingers are often mentioned in descriptions of the army, and sling bullets of lead or stone crop up relatively often in the excavation of Roman military sites. However, we know of no unit specifically described as slingers.
gladius: The Latin word for sword has conventionally been associated by modern scholars with the short, thrusting weapon which was the basic sidearm of the Roman legionary for many centuries.
hastati: The front line of heavy infantry in the manipular legion, consisting of the youngest men.
hoplite: A Greek heavy infantryman armed with a spear, 90-cm (3-ft) round shield (or hoplon), and wearing bronze helmet, armour, and greaves. Such men normally fought in a dense block formation, known as a phalanx.
imago: A standard topped by a bust or image of
the emperor or a member of his family. The imagines were kept with the other standards of the unit as a reminder of their duty to remain loyal to the emperor.
immunis: Soldier exempt from fatigues, often because he possessed a specialist skill or trade.
legatus: Literally a representative, legati or legates were the senior subordinates of a Roman general. Virtually without exception, such men were senators. Under the Principate two types of imperial legate were most important:
(a) the legatus Augusti proparetore who held command in all imperial provinces (apart from Egypt) containing a legionary garrison, and
(b) the legatus legionis who commanded a legion.
legion (legio): In the Republican and early imperial army a legion numbered some 4,000-6,000 men and was the largest and most important sub-unit within an army. By the 4th century ad the size of the legion appears to have shrunk toe. 1,000-1,200.
librarius: Junior clerk in the headquarters of a unit.
limitanei: In late Antiquity the limitanei were the units assigned to garrison a particular region, most often in a frontier area.
Magister Equitum (Master of Horse): The deputy of a Republican dictator. Tradition insisted that the dictator command the infantry, hence his deputy led the cavalry.
Magister Militum: One of a range of titles given to the most senior officers of Late Roman field armies. Also Magister Peditum or Magister Equitum.
maniple (manipulus): In the Republican army two centuries combined to form a tactical unit known as a maniple. It varied in size from c. 60 to 160 men and was commanded by the centurion of the right-hand century.
numerus: Name given to units of irregular auxiliary soldiers under the Principate. Liter the title was adopted by some cavalry units.
optio: A centurion’s deputy and second-incommand of a century.
paenula: A type of cloak frequently worn by soldiers. These fastened together with toggles, were often hooded, and were worn like a poncho.
palatina: Units named palatina were the elite of the field armies in Late Antiquity.
paludamentum: A formal cloak often worn by centurions and other officers. It was common to drape part of the cloak over the left arm.
pilum: The heavy javelin which was the distinctive armament of the Roman legionary from the time of the militia army until at least the end of the Principate.
prefect (praefectus): (a) One of three senior officers leading a Republican allied ala and effectively equivalent to a tribune in a legion.
(b) Governor of an equestrian province, e.g. Judaea until AD 66, and Egypt.
(c) Commander of an auxiliary ala or cohort under the Principate.
(d) Regimental commander in Late Antiquity.
praepositus: Unit commander in the Late Roman army. Apparently virtually synonymous with tribune or prefect.
primi ordines: The centurions of the first cohort of a legion. These men were the most senior in the centurionate, and enjoyed considerable status.
primus pilus: The commander of the first century of the first cohort and the senior centurion of the legion.
principes: The second line of heavy infantrymen in the manipular legion, consisting of men in the prime of life.
probatio: The first stage undergone by potential recruits to the army involving investigation of their legal status and medical condition.
pugio: The short dagger often carried by legionaries.
quaestor, quaestors had predominantly financial responsibilities, but as the second in command of a provincial governor under the Republic, they also at times led troops into battle.
quinquereme: The 'five' was the standard oared warship of the Punic Wars. The name refers to the basic team of rowers. The ship may have had two banks of oars or, more probably, three banks.
sacramentum: The oath of loyalty sworn by soldiers on enlistment. Under the Principate this was taken to the emperor.
sagum: A type of cloak frequently worn by soldiers. It was fastened with a brooch, usually on the right shoulder.
schola: Guard cavalry regiment in the later Roman army.
sesquiplicarius: Soldier receiving one-and-a-half times normal pay, and probably holding a specialist post or acting as a junior officer.
signum: The standard of the century, the signum usually consisted of a number of disks and other decorations mounted on a pole. Some of these standards were topped by an ornamental spearhead, while others had a sculpted hand, often surrounded by a laurel wreath.
signifer. The junior officer who carried the signum standard of a century. In the imperial army he was also responsible for a range of administrative roles within the unit, most notably supervising the soldiers’ pay and savings.
singulares: The elite bodyguards of a senior Roman officer, such as a legionary or provincial legate. These men were normally auxiliaries seconded from their units. The singulares Augusti were an elite cavalry unit drawn from the entire Empire and attached to the praetorian guard.
spatlui: The name conventionally used to describe the longer swords used by Roman cavalrymen and, in Late Antiquity, also many infantrymen.
tesserarius: One of the junior officers within a century, their name was derived from the tessera tablet on which was written the watchword for the day.
trecenarius: Junior officer in the Late Roman army.
tribune (tribunus): (a) Senior staff officer within a legion.
(b) Commander of milliary cohort or ala in the auxilia of the Principate and of a range of regiments in the Late Roman army.
triarii: The third (rear) line of infantry, recruited from the oldest and most experienced soldiers.
trireme: The ‘three’ had been the standard warship of most fleets from the 5th to 4th centuries вс. They were still employed in auxiliary roles by the Romans. It had three banks of oars, each oar rowed by a single man.
vexillation (vexillatio): (a) A detachment of troops operating away from their parent unit or units.
(b) Name given to some cavalry units in the Late Roman army.
incus: After a period of time the informal settlement or canabae surrounding a Roman fort was usually granted the status of vicus. Such settlements supplied the bases with many of their needs.
vigiles: These cohorts were instituted by Augustus to be the fire-brigade and night police of Rome. They were organized along paramilitary lines.