fission (n.)youdaoicibaDictYouDict[fission 词源字典]
1819, "division of a cell or organism," from Latin fissionem (nominative fissio) "a breaking up, cleaving," from past participle stem of findere "to split" (see fissure). Cognate with Old English bitan "to bite." Nuclear physics sense is 1939. As a verb, from 1929.[fission etymology, fission origin, 英语词源]