dis·ser·ta·tion / ˌdisərˈtāshən/ • n. a long essay on a particular subject, esp. one written as a requirement for the Doctor of Philosophy degree: Joe wrote his doctoral dissertation on Thucydides | fig. she went on then into a dissertation on her family's love of Ireland. DERIVATIVES: dis·ser·ta·tion·al / -shənl/ adj.

dissertation †discussion; spoken or (usu.) written discourse containing a discussion at length. XVII. — L. dissertātiō, -ōn-, f. dissertāre discuss, debate, frequent. of disserere treat, examine, discourse, f. DIS- 1 + serere join, connect, join words in composition.