/ɑːrmz/
[noun] Weapons used for fighting, or the symbols and images on a family's or country's official coat of arms. In everyday use, 'arms' can also simply mean the two limbs of the body attached to your shoulders.
The same Latin root that gave soldiers their swords also gave heraldry its shields — 'arms' has always meant both the weapon and the warrior's identity.
The word 'arms' in the sense of weapons travels back to the Latin noun 'arma', meaning tools of war, weapons, or military equipment. This Latin root is ancient, appearing in classical texts by Virgil and Caesar, and it belongs to a deeper Proto-Indo-European root '*ar-', meaning to fit together or join — a reminder that early weapons were carefully crafted, assembled things. From 'arma', the word passed into Old French as 'armes', where it flourished in the language of medieval knights and feudal courts. English picked it up in the 13th century, during the period of heavy French influence that followed the Norman Conquest of 1066, when French was the language of law, nobility, and military life in England.
Once in English, 'arms' quickly took on a double life. On the battlefield, it meant weapons — swords, spears, shields, and later guns. In the tournament and the royal court, it took on the heraldic meaning: the images, symbols, and colours displayed on a knight's shield to identify him in battle. This is why we still speak of a 'coat of arms', a phrase that originally referred to the decorated tunic worn over a knight's armour to display his family's symbols. The College of Arms in London, founded in 1484, continues to grant and record these symbols to this day.
The verb 'to arm', meaning to supply with weapons or to prepare for battle, grew directly from the same Latin 'arma', travelling through Old French 'armer' into Middle English. This gave English a rich family of related words: 'army' came from Old French 'armée', meaning a group of armed people; 'armour' came from Old French 'armure', itself from Latin 'armatura'; and 'armistice' — the formal pause in fighting — combines Latin 'arma' with 'sistere', meaning to stop, arriving in English in the early 18th century and forever linked to November 11, 1918.
The bodily meaning of 'arms' — the limbs of the human body — comes from a completely different Latin word: 'armus', meaning shoulder or upper arm. This 'armus' also traces back to the Proto-Indo-European '*ar-' root, making the weapons and the body parts distant cousins rather than strangers. In Old English, the body's limb was called 'earm', which evolved naturally into the modern English 'arm'. The plural 'arms' for both meanings converged in spelling by the Middle English period, which is why we never think twice about the fact that we bear 'arms' with our 'arms'.
The phrase 'up in arms', meaning angry and ready to protest or fight, dates from at least the 16th century and draws on the military sense. 'Small arms' — a term for hand-held firearms — entered the language in the 17th century as gunpowder technology changed warfare. The 'right to bear arms', enshrined in the American Bill of Rights in 1791, uses 'bear' in its old sense of 'to carry', and 'arms' firmly in its weapons meaning, showing how living language can freeze a moment of history in place. Few English words carry quite so much history — heraldic, military, political, and anatomical — in just four letters.