a formal discourse or treatise in which a subject is examined and discussed; dissertation.
Origin: 1595–1605; < L disquīsītiōn- (s. of disquīsītiō), equiv. to disquīsīt(us) (ptp. of disquīrere to investigate; dis-dis-1+ quaerere to seek, ask) + -iōn--ion
dis·qui·si·tion (dĭs'kwĭ-zĭsh'ən) n. A formal discourse on a subject, often in writing.
[Latin disquīsītiō, disquīsītiōn-, investigation, from disquīsītus, past participle of disquīrere, to investigate : dis-, dis- + quaerere, to search for.]
1605, "subject for investigation," also "systematic search," from L. disquisitionem (nom. disquisitio), from stem of disquirere "inquire," from dis- "apart" + quærere "seek, ask" (see query). Sense of "long speech" first recorded 1647.