'armoury' originates from Old French, specifically the word 'armurerie' (or 'armurie'), where the root 'arme' (from Latin 'arma') meant 'arms' or 'weapons'.

'armoury' changed from Old French 'armurerie' into Middle English forms such as 'armurie'/'armourie' and eventually became the modern English word 'armoury'.

Initially it meant 'a place for arms or equipment', and over time it has retained that primary meaning while also extending metaphorically to mean 'a store or supply of resources or methods'.