1570s, "speaking, speech," especially in debate; 1787 as "way of speaking, manner of expression," from Anglo-French (c. 1300) and Old French parlance, from Old French parlaunce, from parler "to speak" (see parley). In common parlance means "in ordinary language."
"to debate, argue for and against" (mid-14c.), from Old English motian "to meet, talk, discuss, argue, plead," from mot "meeting" (see moot (n.)). Meaning "raise or bring forward for discussion" is from 1680s. Related: Mooted; mooting.
mid-15c., "presentation of formal arguments," from Old French argumentacion (14c.), from Latin argumentationem (nominative argumentatio) "the bringing forth of a proof," noun of action from past-participle stem of argumentari "adduce proof, draw a conclusion," from argumentum (see argument). Meaning "debate, wrangling, argument back and forth" is from 1530s.
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 There is no regular verb to go with it: Dissert (1620s, from French disserter, from Latin dissertare) is obsolete, and dissertate (1766) is marked "Unusual" in OED.
early 15c., "to abate excessiveness, reduce the intensity of;" from Latin moderatus "within bounds, observing moderation;" figuratively "modest, restrained," past participle of moderari "to regulate, mitigate, restrain, temper, set a measure, keep (something) within measure," from PIE root *med- "take appropriate measures." Intransitive sense of "become less violent, severe, rigorous, etc." is from 1670s. Meaning "to preside over a debate" is first attested 1570s. Related: Moderated; moderating.
early 14c., dissencioun, "disagreement in opinion," especially strong disagreement which produces heated debate, from Old French dissension (12c.) and directly from Latin dissensionem (nominative dissensio) "disagreement, difference of opinion, discord, strife," noun of action from past participle stem of dissentire "disagree," from dis- "differently" (see dis-) + sentire "to feel, think" (see sense (n.)).
1871, the French word for "closure, the action of closing," applied to debates in the French Assembly ("action of closing (debate) by will of a majority"), then to the House of Commons and U.S. Congress, from French clôture, from Old French closture (see closure). It was especially used in English by those opposed to the tactic.
In foreign countries the Clôture has been used notoriously to barricade up a majority against the "pestilent" criticism of a minority, and in this country every "whip" and force is employed by the majority to re-assert its continued supremacy and to keep its ranks intact whenever attacked. How this one-sided struggle to maintain solidarity can be construed into "good for all" is inexplicable in the sense uttered. ["The clôture and the Recent Debate, a Letter to Sir J. Lubbock," London, 1882]
"unanswerable fact or argument," 1837, slang, something that "settles" a debate, discussion, conflict, etc.; hence "something astonishing" (1880s). Probably an agent noun from cork (v.) on the notion is of putting a cork in a bottle as an act of finality. Corker in the literal sense of "one who or that which corks" is from 1880.