c. 1500, "a discoverer, one who finds out" (now obsolete), from Latin inventor (fem. inventrix, source of French inventeur (15c.), Spanish inventor, Italian inventore) "contriver, author, discoverer, proposer, founder," agent noun from past-participle stem of invenire "to come upon, find; find out; invent, discover, devise; ascertain; acquire, get earn," from in- "in, on" (from PIE root *en "in") + venire "to come," from a suffixed form of PIE root *gwa- "to go, come." Meaning "one who contrives or produces a new thing or process" is from 1550s.
early 14c., mesuren, "to exercise moderation;" mid-14c., "to deal out or divide up by measure," also "to ascertain spatial dimensions, quantity, or capacity of by comparison with a standard;" from Old French mesurer "measure; moderate, curb" (12c.), from Late Latin mensurare "to measure," from Latin mensura "a measuring, a measurement; thing to measure by," from mensus, past participle of metiri "to measure," from PIE root *me- (2) "to measure." The native verb is mete. Intransitive sense of "to be of a (specified) measure" is from 1670s. To measure up "have the necessary abilities" is 1910, American English. Related: Measured; measuring.
"to know" (archaic), Old English witan (past tense wast, past participle witen) "to know, beware of or conscious of, understand, observe, ascertain, learn," from Proto-Germanic *witanan "to have seen," hence "to know" (source also of Old Saxon witan, Old Norse vita, Old Frisian wita, Middle Dutch, Dutch weten, Old High German wizzan, German wissen, Gothic witan "to know"), from PIE root *weid- "to see." The phrase to wit, almost the only surviving use of the verb, is first recorded 1570s, from earlier that is to wit (mid-14c.), probably a loan-translation of Anglo-French cestasavoir, used to render Latin videlicet (see viz.).
"to allot," Old English metan (West Saxon mæton), "to measure, ascertain the dimension or quantity of; measure out; compare; estimate the greatness of value of" (class V strong verb; past tense mæt, past participle meten), from Proto-Germanic *metana "to measure" (source also of Old Saxon metan, Old Frisian, Old Norse meta, Dutch meten, Old High German mezzan, German messen, Gothic mitan "to measure"), from PIE root *med- "take appropriate measures." Meaning "distribute or apportion by measure" is from c. 1300 and is the surviving sense, used now exclusively with out. Related: Meted; meting.
Old English leornian "to get knowledge, be cultivated; study, read, think about," from Proto-Germanic *lisnojanan (cognates: Old Frisian lernia, Middle Dutch leeren, Dutch leren, Old High German lernen, German lernen "to learn," Gothic lais "I know"), with a base sense of "to follow or find the track," from PIE root *lois- "furrow, track." It is related to German Gleis "track," and to Old English læst "sole of the foot" (see last (n.1)).
From c. 1200 as "to hear of, ascertain." Transitive use (He learned me (how) to read), now considered vulgar (except in reflexive expressions, I learn English), was acceptable from c. 1200 until early 19c. It is preserved in past-participle adjective learned "having knowledge gained by study." Old English also had læran "to teach" (see lere). Related: Learning.
late 14c., poisen, "to have (a specified) weight," a sense now obsolete, from Old French poiser, stressed form of peser "to weigh, be heavy; weigh down, be a burden; worry, be a concern," from Vulgar Latin *pesare, from Latin pensare "to weigh carefully, weigh out, counter-balance," frequentative of pendere (past participle pensus) "to hang, cause to hang; weigh; pay" (from PIE root *(s)pen- "to draw, stretch, spin").
The meaning "to weigh, ascertain by weighing or balancing is from 1590s, hence the meaning "to hold or place in equilibrium or balance," from 1630s (compare equipoise). The intransitive sense of "be balanced or suspended," figuratively "to hang in suspense" is by 1847; the passive sense of "to be ready" (for or to do something) is by 1932. Related: Poised; poising. In 15c. a poiser was an official who weighed goods. The secondary sense of "to ponder, consider" in Latin pensare yielded pensive; that sense was occasional, but rare in Middle English poise.
popularized 1871, American English, (identified throughout the 1870s as "a California word") "young street rowdy, loafer," especially one involved in violence against Chinese immigrants, "young criminal, gangster;" it appears to have been in use locally from a slightly earlier date and may have begun as a specific name of a gang:
The police have recently been investigating the proceedings of a gang of thieving boys who denominate themselves and are known to the world as the Hoodlum Gang. [San Francisco Golden Era newspaper, Feb. 16, 1868, p.4]
Of unknown origin, though newspapers of the day printed myriad fanciful stories concocted to account for it. A guess perhaps better than average is that it is from German dialectal (Bavarian) Huddellump "ragamuffin" [Barnhart].
What the derivation of the word "hoodlum" is we could never satisfactorily ascertain, though several derivations have been proposed; and it would appear that the word has not been very many years in use. But, however obscure the word may be, there is nothing mysterious about the thing; .... [Walter M. Fisher, "The Californians," London, 1876]
early 15c., invencioun, "finding or discovering of something," from Old French invencion (13c.) and directly from Latin inventionem (nominative inventio) "faculty of invention," noun of action from past-participle stem of invenire "to come upon, find; find out; invent, discover, devise; ascertain; acquire, get, earn," from in- "in, on" (from PIE root *en "in") + venire "to come" (from a suffixed form of PIE root *gwa- "to go, come").
The sense of "thing invented" is first recorded 1510s; that of "act or process of finding out how to make or do" is from 1530s.
Invention is applied to the contrivance and production of something, often mechanical, that did not before exist, for the utilization of powers of nature long known or lately discovered by investigation. Discovery brings to light what existed before, but was not known. [Century Dictionary]
The earliest sense of the word in Middle English was "devised method of organization" (c. 1400), a sense now obsolete. The meaning "finding or discovery of something" is preserved in Invention of the Cross, Church festival (May 3) celebrating the reputed finding of the Cross of the Crucifixion by Helena, mother of Constantine, in 326 C.E. The related classical Latin word for "a device, contrivance" was inventum.
c. 1200, prēven, pruven, proven "to try by experience or by a test or standard; evaluate; demonstrate in practice," from Old French prover, pruver "show; convince; put to the test" (11c., Modern French prouver), from Latin probare "to make good; esteem, represent as good; make credible, show, demonstrate; test, inspect; judge by trial" (source also of Spanish probar, Italian probare, and English probe), from probus "worthy, good, upright, virtuous."
This is from PIE *pro-bhwo- "being in front," from *pro-, extended form of root *per- (1) "forward," hence "in front of," + root *bhu- "to be," source also of Latin fui "I have been," futurus "about to be;" Old English beon "to be;" see be.
From early 13c. as "render certain, put out of doubt," also "establish the validity or authenticity of a will, etc." By c. 1300 as "test and find worthy, virtuous, false, etc.," also "find out, discover, ascertain; prove by argument." By mid-14c. as "check the accuracy of." The meaning "be found to be (a hero, coward, etc.) by experience or trial" is by late 14c.
The word had many more senses and broader application in Middle English than Modern English: "to experience; to strive, endeavor; act, accomplish; thrive, succeed." Also in Middle English in a now-obsolete sense of "approve, sanction, praise" (c. 1300; compare approve). Related: Proved; proven; proving. Proving ground "place used for firing cannons for making ballistics tests and testing powder" is by 1837.