/ˈtʃeɪmbər/
[noun] A room, especially a private or formal one, such as a bedroom or a room used for official meetings. It can also refer to an enclosed space inside a machine or structure, like the part of a gun that holds a bullet.
Every time you say 'chamber,' you are speaking an ancient Greek word for a vaulted roof, hidden inside a French disguise.
The word 'chamber' arrived in English in the early 13th century from Old French 'chambre,' meaning a room or private apartment. But that Old French word did not spring from nowhere — it came from Late Latin 'camera,' which itself was borrowed from Ancient Greek 'kamara,' meaning an object with an arched cover, a vaulted room, or a vault. The Greek root likely came from an even older Proto-Indo-European base meaning 'to curve' or 'to bend,' giving us a vivid picture of arched ceilings in ancient buildings.
In Latin, 'camera' evolved into a versatile word meaning any vaulted room or chamber, and it also came to describe the private rooms of important officials. This is why so many formal institutions today still carry the idea of a 'camera' — the Exchequer's room in medieval England, for instance, was managed by officials of the chamber. The Latin 'camera' passed into Old French as 'chambre,' and from there crossed the English Channel with the Norman conquerors after 1066, bringing with it an air of privacy and authority.
In Middle English, 'chamber' first referred primarily to a private bedroom or sleeping room, often the most intimate space in a great house or castle. A nobleman's personal attendant was called a 'chamberlain' — literally 'the keeper of the chamber' — a title of enormous importance that survives in formal use even today. Over the centuries, the word expanded outward from the bedroom, stretching to cover any enclosed or semi-enclosed space that resembled a room: the chamber of a heart, the chamber of a gun, the deliberating chamber of a parliament.
The political sense of 'chamber' — a hall where a legislative body meets — became common in English during the 16th and 17th centuries, mirroring the French usage where the 'Chambre des Députés' was the hall of elected representatives. This gave English expressions like 'the Upper Chamber' and 'the Lower Chamber' of parliament, terms that feel grand and ancient even to modern ears. The idea is always the same: a bounded, enclosed, serious space where important things happen.
Meanwhile, the original Greek ancestor 'kamara' quietly went on to give English another word through a completely different route. The Latin 'camera obscura' — meaning 'dark chamber' — described a box with a tiny hole that projected an image of the outside world onto its inner wall. When photography was invented in the 19th century, the 'camera obscura' was shortened simply to 'camera,' the device we all carry in our pockets today. So 'chamber' and 'camera' are, at their deepest root, the same word — one dressed in French, the other still wearing its Latin coat.