Dissertation
early 17th century (in the sense ‘discussion, debate’): from Latin dissertatio(n- ), from dissertare ‘continue to discuss’, from disserere ‘examine, discuss’.
wiktionary
From Latin dissertātiō, from dissertō.
etymonline
dissertation (n.)
1610s, "discussion, debate" (a sense now obsolete), from Late Latin dissertationem (nominative dissertatio) "discourse," noun of action from past-participle stem of Latin dissertare "debate, argue, examine, harangue," frequentative of disserere "discuss, examine," from dis- "apart" (see dis-) + serere "to join together, put in a row, arrange (words)," from PIE root *ser- (2) "to line up."
Sense of "formal, written treatise" is from 1650s. Meaning "research paper required as a final project for a Ph.D or other doctoral degree" is attested by 1877 in reference to continental universities; it was in use in the U.S. by 1890. Related: Dissertational. There is no regular verb to go with it: Dissert (1620s, from French disserter, from Latin dissertare) is obsolete, and dissertate (1766) is marked "Unusual" in OED.
