Glossary of military terms - O

Obelos

'Spit'. the long iron point of a pilum  or soliferreum  javelin.

Obsidio

Siege.

Ocrea

Greave.

Officialis

Member of administrative staff.

Officium

A - staff.
B - office.

Officium rationum

Accounting office.

Oikeios

Organic. incorporated into permanent strucure of a military unit.

Oiketès

Household retainer. private bodyguard.

Onager

'Wild ass'. torsion gun.

Onagros

'Wild ass'. torsion gun.

Opera vacans

Soldier exempt from fatigue duty. first century AD term for the type of soldier called an immunis  from the second century AD on.

Oppidum

Fortified town.

Oppugnatio

Assault.

Optimas

A - noble, war lord.
B - Byzantine horse guard.

Optimates

Byzantine elite cavalry force.

Optime Maxime, conserva numerus omnium militantium

Best and Greatest, protect the collective of all serving soldiers. motto used on military equipment..

Optio

'Chosen one'.
A - NCO.
B - private with special responsibilities.

Optio ad spem ordinis

NCO selected for promotion to centurionate.

Optio candidatus

NCO singled out for promotion to rank of centurio .

Optio carceris

NCO in charge of the prison cells.

Optio centuriae

'Chosen men of the company'. NCO serving as rearrank officer of a centuria, in the imperial army classed as a duplicarius , a NCO on double basic pay.

Optio centurionis

'Chosen man of the centurion'. NCO serving as rearrank officer of a centuria.

Optio equitum

NCO of the legionary or praetorian horsemen.

Optio fabricae

Soldier or NCO in charge of a work shop.

Optio navaliorum

NCO or specialist soldier in charge of boats.

Optio praetorii

Specialist soldier or NCO attached to headquarters.

Optio principalis

NCO. not all optiones were noncommissioned officers, called principales from the second century on.

Optio speculatorum

NCO of elite cavalry bodyguards.

Optio spei

NCO selected for promotion to centurionate.

Optio statorum

NCO of military constabulary.

Optio tribuni

Assistant to tribune.

Optio valetudinarii

Orderly in charge of hospital.

Optioon

Nco.

Opus

Work. job. task.

Ordinarius/Ordinatus

Centurion.

Ordinatio

A - battle deployment.
B - commissioning as centurio .

Ordo

A - battle line.
B - military unit.
C - post of centurio .

Ordo equester

The equestrian order. Originally the class of wealthy citizens from which the cavalry was recruited, later the class from which many senior officers were drawn.

Origo

Origin.

Origo castris

'Born in the camp'. soldier originating from civilian settlement adjacent to an army base.

Oothismos

The shoving between two phalanges .

Ouetranos

Veteran. discharged soldier.

Ouexillatioon

Detachment. provisional unit. Greek term for vexillatio .

Ornithoboros

'Bird carrier'. unarmed Byzantine NCO who apparently no longer carried an eagle standard.

Oulamos

Squadron. cavalry unit.

Ouragos

Rearrank officer. optio .

Otium castrorum

Time off-duty.

Ovatio

Triumphal entry for victorious commander.