Origin: 1605–15; < Latin dissertātiōn- (stem of dissertātiō), equivalent to dissertāt(us) (past participle of dissertāre; dissert- (see dissert) + -ātus-ate1) + -iōn--ion
1611, from L. dissertationem (nom. dissertatio) "discourse," from dissertare "debate, argue," frequentative of disserere "discuss, examine," from dis- "apart" + serere "to arrange words" (see series). Sense of "formal, written treatise" is 1651.