rigor (n.)youdaoicibaDictYouDict[rigor 词源字典]
late 14c., from Old French rigor "strength, hardness" (13c., Modern French rigueur), from Latin rigorem (nominative rigor) "numbness, stiffness, hardness, firmness; roughness, rudeness," from rigere "be stiff" (see rigid).[rigor etymology, rigor origin, 英语词源]