Online Etymology Dictionary

innovate (v.): 1540s, "introduce as new" (trans.), from Latin innovatus, past participle of innovare "to renew, restore;" also "to change," from in- "into" (see in- (2)) + novus "new" (see new). Intransitive meaning "bring in new things, alter established practices" is from 1590s. Related: Innovated; innovating.
innovation (n.): mid-15c., "restoration, renewal," from Late Latin innovationem (nominative innovatio), noun of action from past participle stem of innovare "to change; to renew" (see innovate). Meaning "a novel change, experimental variation, new thing introduced in an established arrangement" is from 1540s.
innovative (adj.): 1796 (with an isolated use from c. 1600), from innovate + -ive. Related: Innovatively; innovativeness.
innovator (n.): "an introducer of changes," 1590s, from Late Latin innovator, agent noun from innovare "to change" (see innovate).
innovatory (adj.): 1802; see innovate (v.) + -ory.
innuendo (n.): "oblique hint, indiscreet suggestion," usually a deprecatory one, 1670s, from Latin innuendo "by meaning, pointing to," literally "giving a nod to," ablative of gerund of innuere "to mean, signify," literally "to nod to," from in- "at" (see in- (2)) + nuere "to nod" (see numinous).

Originally in English a legal phrase (1560s) from Medieval Latin, with the sense of "to wit," introducing an explanatory or parenthetical clause, it also introduced the derogatory meaning alleged in libel cases, which led to broader meaning. As a verb, from 1706.
Innuit: 1765, from Inupiaq Eskimo inuit "the people," plural of inuk "man, person."
innumerable (adj.): mid-14c., from Latin innumerabilis "countless, immeasurable," from in- "not" (see in- (1)) + numerabilis "able to be numbered," from numerare "to count, number," from numerus "a number" (see number (n.)). Related: Innumerability.
innumerate (adj.): "unacquainted with the basic principles of mathematics," 1959, based on illiterate, with Latin numerus "a number" (see number (n.)). Related: Innumeracy.
Ino: Greek sea-goddess, daughter of Cadmus and Hermione.
inobservant (adj.): 1660s, from Late Latin inobservantem (nominative inobservans) "inattentive, negligent," from in- "not" (see in- (1)) + Latin observans (see observance). Related: Inobservance (1610s).
inoculate (v.): mid-15c., "implant a bud into a plant," from Latin inoculatus, past participle of inoculare "graft in, implant a bud or eye of one plant into another," from in- "in" (see in- (2)) + oculus "bud," originally "eye" (see eye (n.)). Meaning "implant germs of a disease to produce immunity" is from inoculation, originally in reference to smallpox, after 1799, often used in sense of "to vaccine inoculate." Related: Inoculated; inoculating.
inoculation (n.): mid-15c. in horticulture, "act or practice of grafting buds;" 1714 in pathology, "insertion of a form of a virus in order to prevent a more serious attack of it," from Latin inoculationem (nominative inoculatio) "an engrafting, budding," noun of action from past participle stem of inoculare (see inoculate).
inoffensive (adj.): 1590s, from in- (1) "not, opposite of" + offensive (adj.). Related: Inoffensively; inoffensiveness.
inofficious (adj.): c. 1600, "neglecting one's duty;" in law, "not in accord with one's moral duty," 1660s, from Medieval Latin inofficiosus "contrary to duty; harmful," from in- "not, opposite of" (see in- (1) + Latin officiosus "dutiful, obliging" (see officious).
inoperable (adj.): "incapable of being treated by surgical operation," 1856, from in- (1) "not, opposite of" + operable.
inoperative (adj.): "not working," 1630s, from in- (1) "not, opposite of" + operative (adj.).
inopportune (adj.): 1530s, from Late Latin inopportunus "unfitting," from in- "not" + opportunus "favorable, convenient" (see opportune). Rare or obsolete in 18c. Related: Inopportunely; inopportuneness; inopportunity.
inordinate (adj.): late 14c., "not ordered, lacking order or regularity," from Latin inordinatus "unordered, not arranged," from in- "not, opposite of" (see in- (1)) + ordinatus, past participle of ordinare "to set in order" (see order (n.)). Sense of "immoderate, excessive" is from notion of "not kept within orderly limits." Related: Inordinately; inordinateness.
inorganic (adj.): 1727, "without the organized structure which characterizes living things," from in- (1) "not, opposite of" + organic (adj.). Inorganical in this sense is from 1670s. Meaning "not arriving by natural growth" is recorded from 1862.
inpatient (n.): also in-patient, "patient lodged and fed, as well as treated, at a hospital or infirmary," 1760, from in (adj.) + patient (n.). As an adjective from 1959.
input (n.): 1753, "a sum (of cash) put in, a sharing, contribution," from verbal phrase; see in (adv.) + put (v.). Meaning "energy supplied to a device or machine" is from 1902, later of electronic devices; computing sense of "data fed into a machine" is from 1948, though this is perhaps from the verb in the computing sense.
input (v.): late 14c., "put on, impose," from in (adv.) + put (v.). Modern sense "feed data into a machine" is from 1946, a new formation from the same elements.
inquest (n.): late 13c., enquest, an-queste "legal or judicial inquiry," especially one before a jury, from Old French enqueste "inquiry" (Modern French enquête), from Vulgar Latin *inquaestia (source also of Italian inchiesta), from Latin inquisita (res) "(a thing) looked into; an inquiry," from fem. past participle of Latin inquirere "to seek after, search for" (see inquire). The form with in- prevailed from 18c.
inquiline (n.): 1640s, "a lodger," from Latin inquilinus "an inhabitant of a place not his own," from *incolinus, from incola "an inhabitant," from in- "in" (see in- (2)) + colere "inhabit, dwell" (see colony). Zoological sense of "animal living in the abode of another, a commensal" is from 1865.
inquire (v.): c. 1300, enqueren, anqueren, "to ask (a question), ask about, ask for (specific information); learn or find out by asking, seek information or knowledge; to conduct a legal or official investigation (into an alleged offense)," from Old French enquerre "ask, inquire about" (Modern French enquérir) and directly from Medieval Latin inquerere, from in- "into" (see in- (2)) + Latin quaerere "ask, seek" (see query (v.)), in place of classical Latin inquirere "seek after, search for, examine, scrutinize." The English word was respelled 14c. on the Latin model, but half-Latinized enquire persists. Related: Inquired; inquiring.
inquirer (n.): 1560s, "one who inquires, a seeker, an investigator," agent noun from inquire.
inquiring (adj.): "given to inquiry or investigation," 1590s, present-participle adjective from inquire (v.). Related: Inquiringly.
inquiry (n.): early 15c., enquery, "a judicial examination of facts to determine truth;" mid-15c. in general sense "attempt to learn something, act or fact of inquiring," probably an Anglo-French noun developed from enqueren "to inquire" (see inquire). Respelled from mid-16c. to conform to Latin.
inquisition (n.): late 14c., "judicial investigation, act or process of inquiring," from Old French inquisicion "inquiry, investigation" (12c., Modern French inquisition), from Latin inquisitionem (nominative inquisitio) "a searching into, a seeking; legal examination, a seeking of grounds for accusation," noun of action from past participle stem of inquirere (see inquire).

In Church history, inquisitors were appointed from 382 C.E. to root out heretics; the ecclesiastical court appointed 13c. by Innocent III to suppress heresy never operated in Britain. The English word began to be used in this sense (and with a capital initial letter) after c. 1500, and usually refers to the office's reorganization 1478-1483 in Spain, where it fell under the control of the state as what is commonly called the Spanish Inquisition, noted especially for its severity, secrecy, and the number of its victims.
inquisitive (adj.): late 14c., from Old French inquisitif, from Late Latin inquisitivus "making inquiry," from Latin inquisit-, past participle stem of inquirere "seek after, search for; examine, investigate" (see inquire).
An housbonde shal nat been Inquisityf of goddes pryuetee nor of his wyf. [Chaucer, "Miller's Prologue"]
Related: Inquisitively; inquisitiveness.
inquisitor (n.): c. 1400, "an inspector, one who makes inquiries," from Anglo-French inquisitour, Old French inquisiteur, or directly from Latin inquisitor "searcher, examiner; a legal investigator, collector of evidence," agent noun from Latin inquirere (see inquire). As the title of an officer of the Inquisition, from 1540s. Related: Inquisitorial. Of the fem. forms, inquisitress (1727) is senior to inquisitrix (1825).
inro: 1610s, from Japanese, from Chinese yin "seal" + lung "basket." The small ornamental baskets originally held seals, among other small items.
inroad (n.): 1540s, "hostile incursion, raid, foray," from in- (2) "in;" second element is road (n.) in the obsolete sense of "riding;" related to raid (v.). Related: Inroads.
insalubrious (adj.): 1630s, from Latin insalubris "unhealthy, unwholesome," or else a native formation from in- (1) "not, opposite of" + salubrious. Related: Insalubriety.
insane (adj.): 1550s, of persons, "mentally damaged," from Latin insanus "mad, insane, of unsound mind; outrageous, excessive, extravagant," from in- "not" (see in- (1)) + sanus "well, healthy, sane" (see sane). In reference to actions, "irrational, evidencing madness," from 1842 in English. The noun meaning "insane person" is attested from 1786. For the notion of insanity as sickness, compare lunatic; and Italian pazzo "insane," originally a euphemism, from Latin patiens "suffering." German verrückt, literally past participle of verrücken "to displace," "applied to the brain as to a clock that is 'out of order' " [Buck].
insanity (n.): 1580s, "state of being insane, seriously impaired state of mental functioning," from Latin insanitatem (nominative insanitas) "unhealthfulness, unsoundness, disease," noun of quality from insanus "mad, insane; outrageous, excessive" (see insane). Meaning "extreme folly" is from 1844. The Latin abstract noun was insania ""unsoundness of mind, madness, frenzy."
insatiability (n.): 1650s, from Late Latin insatiabilitas, from Latin insatiabilis "not to be satisfied" (see insatiable). Possibly via French insatiabilité (16c.).
insatiable (adj.): early 15c., insaciable, from Old French insaciable "ravenous" (15c., Modern French insatiable), or directly from Latin insatiabilis "not to be satisfied," from in- "not, opposite of" (see in- (1)) + satiabilis, from satiare (see satiate). Related: Insatiably; insatiableness.
insatiate (adj.): "not to be satisfied," mid-15c., insaciate, from Latin insatiatus "unsatisfied," from in- "not, opposite of" (see in- (1)) + satiatus, past participle of satiare "to fill, satisfy" (see satiate).
inscribe (v.): 1550s, "to write on or in" (something durable and conspicuous), from Latin inscribere "to write in or on," (see inscription). Meaning "to dedicate (by means of an inscription)" is from 1640s. Form inscriven is from late 14c. Related: Inscribed; inscribing.
inscription (n.): late 14c., from Latin inscriptionem (nominative inscriptio) "a writing upon, inscription," noun of action from past participle stem of inscribere "inscribe, to write on or in (something)," from in- "in" (see in- (2)) + scribere "to write" (see script (n.)). Related: Inscriptional.
inscrutability (n.): 1650s, from inscrutable + -ity.
inscrutable (adj.): "that cannot be discovered by searching, mysterious," c. 1500, from Late Latin inscrutabilis, from in- "not, opposite of" (see in- (1)) + *scrutabilis, from scrutari "examine, ransack" (see scrutiny). Related: Inscrutably; inscrutableness.
insect (n.): c. 1600, from Latin (animal) insectum "(animal) with a notched or divided body," literally "cut into," noun use of neuter past participle of insectare "to cut into, to cut up," from in- "into" (see in- (2)) + secare "to cut" (see section (n.)).

The Latin word is Pliny's loan-translation of Greek entomon "insect" (see entomology), which was Aristotle's term for this class of life, in reference to their "notched" bodies. First in English in 1601 in Holland's translation of Pliny. In zoology, in reference to a class of animals, 1753. Translations of Aristotle's term also form the usual word for "insect" in Welsh (trychfil, from trychu "cut" + mil "animal"), Serbo-Croatian (zareznik, from rezati "cut"), Russian (nasekomoe, from sekat "cut"), etc. Insectarian "one who eats insects" is attested from 1893.

Among the adjectival forms that have been tried in English (and mostly rejected by disuse) are insectile (1620s), insectic (1767), insective (1834), insectual (1849), insectine (1853), insecty (1859), insectan (1888).
insectarium (n.): 1872, from insect + -arium, abstracted from aquarium, etc.
insecticide (n.): "substance which kills insects," 1866 (from 1865 as an adjective), from insect + -cide. Earlier as a type of machine (1856). Related: Insecticidal (1857).
insectivore (n.): 1863, from French insectivore (1817), from Latin insectivorus, from comb. form of insectum (see insect) + vorare "devour, swallow" (see voracity).
insectivorous (adj.): 1610s; see insect + -vorous. The mammalian class of Insectivora is from 1821; insectivore (n.) is from 1858 (both are earlier in French).
insecure (adj.): 1640s, "unsafe," also "not fully assured, not free from fear or doubt," from Medieval Latin insecurus, from in- "not" (see in- (1)) + Latin securus (see secure (adj.)). Psychological sense dates from 1935. (insecurity in the psychological sense dates from 1917.) Related: Insecurely.