cathedralyoudaoicibaDictYouDict[cathedral 词源字典]
cathedral: [13] Cathedral is a shortening of cathedral church, which was originally the ‘church housing the bishop’s throne’. For ultimately cathedral comes from Greek kathédrā (source also of English chair), a compound noun meaning ‘seat’, formed from katá- ‘down’ and *hed- ‘sit’. The adjectival form was created in late Latin as cathedrālis, and reached English via Old French. The notion of the bishop’s authority residing in his throne recurs in see, which comes from Latin sēdem ‘seat’, a relative of English sit.
=> chair[cathedral etymology, cathedral origin, 英语词源]
cathedral (n.)youdaoicibaDictYouDict
1580s, "church of a bishop," from phrase cathedral church (c. 1300), partially translating Late Latin ecclesia cathedralis "church of a bishop's seat," from Latin cathedra "an easy chair (principally used by ladies)," also metonymically, as in cathedrae molles "luxurious women;" also "a professor's chair;" from Greek kathedra "seat, bench," from kata "down" (see cata-) + hedra "seat, base, chair, face of a geometric solid," from PIE root *sed- (1) "to sit" (see sedentary).

It was born an adjective, and attempts to cobble further adjectivization onto it in 17c. yielded cathedraical (1670s), cathedratic (1660s), cathedratical (1660s), after which the effort seems to have been given up.