monad (n.)youdaoicibaDictYouDict[monad 词源字典]
"unity, arithmetical unit," 1610s, from Late Latin monas (genitive monadis), from Greek monas "unit," from monos "alone" (see mono-). In Leibnitz's philosophy, "an ultimate unit of being" (1748). Related: Monadic.[monad etymology, monad origin, 英语词源]