vegetarian (n.)youdaoicibaDictYouDict[vegetarian 词源字典]
1839, irregular formation from vegetable (n.) + -arian, as in agrarian, etc. "The general use of the word appears to have been largely due to the formation of the Vegetarian Society in Ramsgate in 1847" [OED]. As an adjective from 1849.[vegetarian etymology, vegetarian origin, 英语词源]