detentyoudaoicibaDictYouDict[detent 词源字典]
"A catch in a machine which prevents motion until released", Late 17th century (denoting a catch in a clock): from French détente, from Old French destente, from destendre 'slacken', from des- (expressing reversal) + Latin tendere 'to stretch'.[detent etymology, detent origin, 英语词源]