quietus
/kwaɪˈiːtəs/noun
(pl. quietuses)
1- death or something that causes death, regarded as a release from life（被视为解脱的）死, 致死物。
1.1
- archaic something that has a calming or soothing effect〈古〉起安静作用的东西; 遏制物。
词源
late Middle English: abbreviation of medieval Latin quietus est 'he is quit' （see QUIT1）， originally used as a form of receipt or discharge on payment of a debt.