perilous (adj.)youdaoicibaDictYouDict[perilous 词源字典]
c. 1300, from Old French perillos "perilous, dangerous" (Modern French périlleux) "dangerous, hazardous," from Latin periculosus "dangerous, hazardous," from periculum "a danger, attempt, risk" (see peril). Related: Perilously; perilousness.[perilous etymology, perilous origin, 英语词源]