Origins
The English word 'chair' conceals a remarkable journey from ancient Greek philosophy halls to the most ordinary object in a modern home. It descends from Middle English 'chaiere,' borrowed from Old French 'chaiere' (modern French split this into 'chaire,' a pulpit or professorial chair, and 'chaise,' an everyday seat). The Old French word came from Latin 'cathedra,' which was itself borrowed from Greek 'kathedra,' a compound of 'kata' (down) and 'hedra' (seat, base). The Greek word literally meant 'a sitting-down place' — the spot where a person settled to sit.
In Greek usage, 'kathedra' was associated with teachers and philosophers. It was the seat from which a master instructed students, giving it an early association with intellectual authority. When Latin absorbed the word, this connotation intensified. A Roman 'cathedra' was specifically a chair with a back and sometimes armrests — a distinguished piece of furniture in a world where most people sat on stools, benches, or the ground. Senators, magistrates, and teachers sat in cathedrae; ordinary citizens did not.
The early Christian church adopted the term for the bishop's official seat, the physical throne from which he presided over his flock. A church that housed this episcopal seat became an 'ecclesia cathedralis' — a cathedral church — shortened eventually to simply 'cathedral.' The phrase 'ex cathedra' (from the chair) came to signify speech delivered with the full weight of authority, and in Roman Catholic doctrine it specifically refers to papal pronouncements made with infallible authority.
Old English Period
When the word entered English through Old French after the Norman Conquest, it retained its sense of elevated authority. In the thirteenth and fourteenth centuries, a 'chair' was emphatically not everyday furniture. It was a seat of honor — the lord's chair at the head of the hall, the bishop's throne, the master's seat. Common people sat on benches ('bench' from Old English 'benc') or stools ('stool' from Old English 'stōl,' which itself originally meant any kind of seat, including a throne).
The democratization of the chair — its transformation from a symbol of rank to a common piece of furniture — occurred gradually during the sixteenth and seventeenth centuries, as furniture-making techniques improved and domestic comfort became more widely accessible. By the eighteenth century, chairs were standard household items across much of Western Europe. But the old sense of authority persists in 'chairman' (the person who occupies the chair of authority at a meeting), 'to chair a meeting' (to preside over it), 'endowed chair' (a distinguished professorship), and 'chair' as a verb meaning to carry someone in triumph in a sedan chair.
The phonological evolution from Latin 'cathedra' to English 'chair' is a textbook example of how drastically French sound changes could reshape Latin words. The initial Latin 'ca-' became Old French 'cha-' through palatalization before 'a.' The middle syllable '-the-' was lost entirely through syncope. The final '-dra' softened to '-ire' and then '-ir,' yielding 'chaiere' and eventually English 'chair.' Meanwhile, French itself later developed the variant 'chaise' through a dialectal pronunciation of 'r' as 'z' — a feature of Parisian speech that was sometimes adopted into standard French.