carbon dioxide (n.)youdaoicibaDictYouDict[carbon dioxide 词源字典]
1869, so called because it consists of one carbon and two oxygen atoms. The chemical was known since mid-18c. under the name fixed air; later as carbonic acid gas (1791). "The term dioxide for an oxide containing two atoms of oxygen came into use in the middle of the 19th century." [Flood].[carbon dioxide etymology, carbon dioxide origin, 英语词源]