fervor (n.)youdaoicibaDictYouDict[fervor 词源字典]
mid-14c., "warmth or glow of feeling," from Old French fervor "heat; enthusiasm, ardor, passion" (12c., Modern French ferveur), from Latin fervor "a boiling, violent heat; passion, ardor, fury," from fervere "to boil; be hot" (see brew (v.)).[fervor etymology, fervor origin, 英语词源]