1550s, "in conclusion," from conclusive + -ly (2). Meaning "decisively" is recorded from 1748.
1660s, from in- (1) "not, opposite of" + conclusive. Related: Inconclusively. Inconclusion is "rare," perhaps because it could mean either "reaching no conclusion" or "reaching an unwarranted conclusion." Related: Inconclusiveness.
1610s, "occurring at the end," from French conclusif, from Late Latin conclusivus, from conclus-, past participle stem of Latin concludere "to shut up, enclose," from assimilated form of com "together" (see con-) + -cludere, combining form of claudere "to shut" (see close (v.)). Meaning "definitive, decisive, convincing, being so forcible as not to admit of contradiction" (on the notion of "leading to a logical conclusion," and thus putting an end to debate) is from 1640s. Related: Conclusiveness.
early 15c., "conclusive, logical," also "following as an effect or result," from Old French consequent "following, resulting" and directly from Latin consequentem (nominative consequens) "following, consequent," present participle of consequi "to follow after," from assimilated form of com "with, together" (see con-) + sequi "to follow" (from PIE root *sekw- (1) "to follow"). Related: Consequently.
early 14c., "person or thing that clinches" (i.e., secures nails by bending down or riveting the pointed end), late 15c. as a class of shipyard worker; agent noun from clinch (v.). As a type of nail, from 1735; as a conclusive statement, argument, etc., 1737. Clincher-built "made of boards or metal pieces which overlap one another" is from 1769.
late 14c., "ending, determining, conclusive," from Old French definitif (12c.), from Latin definitivus "explanatory, definitive," in Late Latin "definite," from definit-, past-participle stem of definire "to limit, determine, explain," from de "completely" (see de-) + finire "to bound, limit," from finis "boundary, end" (see finish (v.)). As a noun, in grammar, "a defining or limiting word," by 1751. Related: Definitively; definitiveness.
large sea fish, edible and widely distributed in colder seas, mid-14c. (late 13c. in a surname, Thomas cotfich), of unknown origin; despite similarity of form it has no conclusive connection to the widespread Germanic word for "bag" (represented by Old English codd, preserved in cod-piece). Codfish is from 1560s. Cod-liver oil, known at least since 1610s, was recommended medicinally from 1783 but did not become popular as a remedy until after 1825.
1830, with many spelling variants, "a decisive blow" (also, figuratively "a conclusive argument"), American English, a fanciful formation from sock (v.1) "hit hard," perhaps via a comical mangling of doxology, on a notion of "finality." The meaning "something exceptional" is attested from 1838.
Sockdologizing likely was one of the last words President Abraham Lincoln heard. During the performance of Tom Taylor's "Our American Cousin," assassin John Wilkes Booth (who knew the play well) waited for the laugh-line:
Don't know the manners of good society, eh? Well, I guess I know enough to turn you inside out, old gal—you sockdologizing old man-trap.
Amid the noise as the audience responded, Booth fired the fatal shot.
late 14c., "indestructible, unable to be loosened," also figuratively, of problems, etc., "incapable of being solved or explained," from Old French insoluble or directly from Latin insolubilis "that cannot be loosened," from in- "not" (see in- (1)) + solubilis "that can be loosened" (see soluble).
It was a tacit conviction of the learned during the Middle Ages that no such thing as an insoluble question existed. There might be matters that presented serious difficulties, but if you could lay them before the right man -- some Arab in Spain, for instance, omniscient by reason of studies into the details of which it was better not to inquire -- he would give you a conclusive answer. The real trouble was only to find your man. [Gertrude Bell, "The Desert and the Sown," 1907]
Meaning "incapable of being dissolved in a liquid" is from 1713.