Lexicon of Roman military terms

Accensus – reservist or light legionary infantry soldier
Acceptarius – discharged soldier
Actarius – military or camp clerk
Adiutor- camp or headquarters adjutant or assistant
Aenator – military musician such as a bugler or hornblower
Agrimensor – surveyor (a type of immunes)
Aquilifer – holder the legionary Eagle
Ala – auxilliary cavalry unit (16 turmae, 480 cavalrymen)
Alaris – cavalryman serving in an ala, armed with hasta (spear), spatha (broadsword), parma (medium shield) and lorica hamata (chain mail)
Architecti – engineer or siege engine constructor
Armicustos – soldier tasked with the administration and supply of weapons and equipment (quartermaster)
Ballistarius – ballista or siege engine operator
Beneficiarius – soldier performing an extraordinary task such as military policing or a special assignment
Bucinator – bugler
Cacula – unenlisted camp servant
Capsarior – medical orderly
Causarius – soldier discharged for wounds or other medical reasons
Centuria – basic infantry unit of legion (80 men)
Centurion – officer rank, in charge of centuria
Clinicus – medic
Cohort – tactical unit in a legion (6 centuria or 480 men)
Contubernium – means “tent”, infantry squad (8 men)
Cornicen – hornblower
Doctore – trainer, subdivisions for everything from weapons to hornblowing
Draconarius – cavalry standard bearer
Decurion – leads a 10 horsemen group in turmae
Decanus – leads a contubernium
Discens – Miles in training for an immunis position
Dux – a general in charge of two or more legions
Evocatus – soldiers in the Roman army, who had served out their time and obtained their discharge (missio), but had voluntarily enlisted again at the invitation of the consul or other commander
Frumentarii – secret intelligence service of Roman army
Hastiliarius – weapons instructor
Imaginifer – standard-bearer carrying the imago the standard which bore a likeness of the Emperor and at later dates his family
Immunes – those soldiers of the military of ancient Rome who were “immune” from combat duty and fatigues through having a more specialist role within the army
Legatus – general in the Roman army, literally the “deputy” of the emperor, who was the titular commander-in-chief
Legion – strategical unit of Roman army (5,400 men)
Legionary – the heavy infantry that was the basic military unit of the ancient Roman army in the period of the late Roman Republic and the Roman Empire, armed with gladius (short sword), pilum (javelin), scutum (large shield) and lorica segmentata (segmented armor)
Medicus – physician or combat medic. Specializations included surgery (medicus vulnerarius), ophthalmology (medicus ocularius) and even veterinary (medicus veterinarius). At least some held rank equivalent to a centurion
Miles – The basic private level foot soldier (miles gregarius)
Optio – One per century as second-in-command to the centurion. Could also fill several other specialized roles on an ad hoc basis.
Pedites – the infantry of the early army of the Roman kingdom. The majority of the army in this period.
Peditatus – term referring to any infantryman in the Roman Empire
Pilus Prior – The commander of the first centuria of each cohort
Pilus Posterior – Deputy to the pilus prior
Praefectus Castrorum – camp prefect, third-in-command of the legion, also responsible for maintaining the camp, equipment and supplies. Usually a former primus pilus
Praetorians – special force of bodyguards used by Roman Emperor
Prima Cohort – “first” cohort in a legion (6 reinforced centuria, 960 men)
Primus Pilus – “first file”, commanding centurion of the prima cohort and the senior centurion of the entire legion
Principales – a group of ranks, including aquilifer, signifer, optio and tesserarius (NCOs)
Quaestionarius – an interrogator or torturer
Retentus – a soldier kept in service after serving required term
Sagittarii – archers, including horse-riding auxiliary archers recruited mainly in the Eastern Empire and Africa
Salararius – a soldier enjoying special service conditions or hired as a mercenary
Scorpionarius – operator of a scorpio (dart-thrower)
Signifer- Standard bearer of the Roman Legion
Socii – Conscripts
Speculatores – scouts and reconnaissance element of the Roman army
Supernumerarii – kind of supernumerary soldier who served to fill the places of those who were killed or disabled by their wounds (reserve)
Tesserarius – watch or guard commander, one per century
Tribunus Militum – military tribune of senatorial rank, second in command of a legion
Turmae – auxilliary cavalry squadron (30 cavalrymen)
Venator – hunter (a type of immunes)
Vexillarius – standard-bearer (carried the vexillum)

Lexicon of Roman military terms

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