(historical) A sword seen as a being a part of someone's set of arms or military accoutrements; a warrior's regimental or official sword.

plural of arming sword

plural of spiral arm

(astronomy) A section of a spiral galaxy that coils out from the centre.

plural of arms race

An arm connected to the output shaft of a steering gear, aimed at moving the steering linkage to steer a vehicle's front wheels

comrade in arms (fellow combatant or soldier)

plural of armed robbery

(law) An theft where the thieves are carrying weapons.

(physics) The perpendicular distance from a pivot to a point undergoing torque