dissertation (n.)youdaoicibaDictYouDict[dissertation 词源字典]
1610s, "discussion, debate," from Latin dissertationem (nominative dissertatio) "discourse," noun of action from past participle stem of dissertare "debate, argue, examine, harangue," frequentative of disserere "discuss, examine," from dis- "apart" (see dis-) + serere "to arrange words" (see series). Sense of "formal, written treatise" is 1650s.[dissertation etymology, dissertation origin, 英语词源]
dissertateyoudaoicibaDictYouDict
"Discourse on a particular subject", Mid 18th century: from Latin dissertat-, from dissertare 'to continue to discuss'.