/ˈɑːrmər/
[noun] A protective covering, traditionally made of metal, worn by soldiers in battle to defend the body from weapons. In modern use, it can also refer to any strong protective layer, such as the metal plating on a military vehicle.
The word 'armour' traces back to Latin 'armare', meaning 'to arm' — the same root that gave soldiers, weapons, and armies their names.
The story of 'armour' begins in ancient Rome, with the Latin verb 'armare', meaning 'to equip with weapons' or 'to arm'. This verb came from the Latin noun 'arma', which referred to weapons and tools of war in a broad sense — shields, swords, and anything a soldier might carry into battle. The Romans were precise about the word: 'arma' covered defensive and offensive equipment alike, making it one of the most militarily loaded words in the Latin language.
When the Roman Empire fell and Latin fragmented into the Romance languages of medieval Europe, 'arma' evolved naturally into Old French as 'armeure' or 'armure', meaning a suit of protective gear worn by a fighter. This Old French form drew on both the Latin root and the practical reality of medieval warfare, in which knights wore increasingly elaborate metal suits. The word carried the sense not just of individual pieces of metal, but of a complete system of protection — a full kit for surviving combat.
English absorbed 'armure' from Old French during the 13th century, at a time when the Norman French influence on English was still very strong. The Normans, who had conquered England in 1066, brought with them their language, their culture, and their way of making war — including the heavily armoured knight on horseback. The word arrived in Middle English as 'armure' and was eventually spelled 'armour', following the British preference for the '-our' ending inherited from French, as opposed to the American '-or' spelling seen today.
What is particularly fascinating about this word family is just how many common English words descend from the same Latin root 'arma'. Latin 'arma' → Old French 'armée' → English 'army'. Latin 'armare' → Old French 'armer' → English 'arm' (as a verb, meaning to equip with weapons). Latin 'arma' → Medieval Latin 'armatura' → Old French 'armeure' → English 'armature', which today refers to the framework of a sculpture or the rotating part of an electric motor. Even 'alarm' travels this path: Latin 'arma' → Italian 'all'arme' (literally 'to the weapons!', a battle cry) → French 'alarme' → English 'alarm'.
Over the centuries, the meaning of 'armour' has expanded well beyond the battlefield. By the 20th century, the word was applied to the steel plating of tanks and warships, and in modern English it is freely used in metaphorical contexts — emotional armour, the armour of confidence, the armour of ignorance. Writers and poets seized on the image of the protective shell to describe any defence a person builds around themselves, giving this ancient military term a rich and deeply human second life. The knight may have vanished from the battlefield, but armour, as a concept, has never left us.