Online Etymology Dictionary

initiand (n.): "one about to be initiated," 1913, from Latin initiand, gerundive of initiare "to begin, initiate; instruct in mysteries" (see initiate (v.)).
initiate (n.): "one who has been initiated" (in secret doctrines, etc.), 1732, from obsolete or archaic past participle adjective initiate "initiated, instructed in secret knowledge" (c. 1600), from Latin initiatus (see initiate (v.)).
initiate (v.): c. 1600, "introduce to some practice or system," also "begin, set going," from Late Latin initiatus, past participle of initiare "to begin, originate," in classical Latin only in the sense "to instruct in mysteries or sacred knowledge." This is from initium "a beginning; an entrance," also in plural initia "constituent parts; sacred mysteries," a noun use of the neuter past participle of inire "to go into, enter upon, begin," from in- "into, in" (see in- (2)) + ire "to go" (see ion).

In some senses the English word is a back-formation from initiation. Related: Initiated; initiates; initiating; initiator.
initiation (n.): 1580s, from Middle French initiation or directly from Latin initiationem (nominative initiatio) "participation in secret rites," noun of action from past participle stem of initiare "originate, initiate," from initium "a beginning" (see initial (adj.)).
initiative (n.): "power of initiating," 1775, from French initiative (16c.), from Latin initiatus, past participle of initiare "to begin," from initium "a beginning" (see initial (adj.)). From 1793 as "disposition to take the lead." Phrase take the initiative recorded by 1815.
initiatory (adj.): 1610s, from initiate (v.) + -ory.
inject (v.): c. 1600, in medicine, from specialized sense of Latin iniectus "a casting on, a throwing over," past participle of inicere "to throw in or on; insert, bring into," from in- "in" (see in- (2)) + -icere, comb. form of iacere "to throw" (see jet (v.)). Related: Injectable; injected; injecting.
injection (n.): "a forcing of a fluid into a body" (with a syringe, etc.), early 15c., from Old French iniection (14c.) or directly from Latin iniectionem (nominative iniectio) "a throwing in," noun of action from past participle stem of inicere "to throw in or on" (see inject).
injector (n.): 1727, agent noun from inject (v.).
injudicious (adj.): 1640s, "incapable of judging aright, wanting good judgement," from in- (1) "not, opposite of" + judicious. Meaning "ill-advised" is from 1711. In the older sense the earlier English word was injudicial (c. 1600). Related: Injudiciously; injudiciousness.
Injun (n.): 1812 (from 1683 as Ingin), a spelling representing the early American English colloquial pronunciation of Indian (q.v.). Honest Injun as an asseveration of truthfuless is first recorded 1868, from the notion of assurance extracted from Indians of their lack of duplicity in a particular situation.
"Honest Injun?" inquired Mr. Wilder, using a Western phrase equivalent to demanding of the narrator of a story whether he is strictly adhering to the truth. ["The Genial Showman," London, 1870]
The noun phrase honest Indian itself is attested from 1676 in Massachusetts.
injunction (n.): early 15c., from Late Latin iniunctionem (nominative iniunctio) "a command," noun of action from past participle stem of Latin iniungere "impose, inflict, bring upon," literally "attach to," from in- "on" (see in- (2)) + iungere "to join" (see jugular).
injunctive: 1620s, from Latin iniunct-, past participle stem of iniungere "impose; attach to" (see injunction) + -ive. As a term in grammar, from 1910.
injure (v.): mid-15c., "do an injustice to, dishonor," probably a back-formation from injury, or else from Old French injuriier "to damage; offend," from Latin iniuriari "do an injury," from iniuria. Injury itself also served as a verb meaning "to injure, hurt, harm" (late 15c.). Related: Injured; injuring.
injurious (adj.): early 15c., "abusive," from Old French injurios "unjust; harmful" (14c., Modern French injurieux) and directly from Latin iniuriosus "unlawful, acting unjustly, wrongful, harmful," from iniuria "injustice, unlawful violence, insult" (see injury). Related: Injuriously; injuriousness.
injury (n.): late 14c., "harm, damage, loss; a specific injury," from Anglo-French injurie "wrongful action" (Old French injure, 13c.), from Latin iniuria "wrong, an injustice, insult, unlawful violence, assault, damage, harm," noun use of fem. of iniurius "wrongful, unjust, unlawful," from in- "not, opposite of" (see in- (1)) + ius (genitive iuris) "right, law" (see jurist).
injustice (n.): late 14c., from Old French injustice "unfairness, injustice" (14c.), from Latin iniustitia "unfairness, injustice," from iniustus "unjust, wrongful, unreasonable, improper, oppressive," from in- "not" (see in- (1)) + iustus "just" (see just (adj.)). Injust (adj.) is attested from late 15c., from French, but unjust is the usual English word.
ink (n.): "the black liquor with which men write" [Johnson], mid-13c., from Old French enche, encre "dark writing fluid" (12c.), earlier enque (11c.), originally enca, from Late Latin encaustum, from Late Greek enkauston. This is the neuter of the past-participle adjective enkaustos "burned in," from the stem of enkaiein "to burn in," from en- "in" (see en- (1)) + kaiein "to burn" (see caustic).

In Pliny the word is the name of a kind of painting executed by fire or heat. Later it was the name of the purple-red ink, the sacrum encaustum, used by the Roman emperors to sign their documents; this was said to have been obtained from the ground remains of certain shellfish, formed into writing fluid by the application of fire or heat, which explained the name. In the Code of Justinian, the making of it for common uses, or by common persons, was prohibited under penalty of death and confiscation of goods.
It denoted a kind of painting practised by the ancients, in which the crayon was dipped in wax of various colours. Encausto pingere is to practise this art, paint in encaustic or enamel. Encaustum afterwards came to signify an ink for the purpose of writing; and the "sacred encaustum" of Justinian's Code was an ink which the Roman Emperors used for imperial subscriptions. It was of the imperial colour, reddish purple, and was made of the purple dye, prepared in some way by the application of fire. (So that in this use of the word, the notion of burning which there is in the etymology, is still retained.) [from footnote in "The Life, Letters, and Sermons of Bishop Herbert de Losinga," Oxford, 1878]
The usual words for "ink" in Latin was atramentum (source of Old French arrement), literally "anything that serves to dye black," from ater "black;" the Greek word was melan, neuter of melas "black." The Old English word for it was blæc, literally "black," and compare Swedish bläk, Danish blæk "ink." Spanish and Portuguese (tinta) and German (tinte) get their "ink" words from Latin tinctus "a dyeing."

Donkin credits a Greek pronunciation, with the accent at the front of the word, for the French evolution; the same Latin word, behaving regularly, became inchiostro (with excrescent -r-) in Italian, encausto in Spanish. As an adjective, inken (c. 1600) occasionally has been used. Ink-slinger, contemptuous for "journalist," is from 1870. The psychologist's ink-blot test attested from 1915.
ink (v.): "to mark or stain in ink," 1560s, from ink (n.). Meaning "to cover (a printing plate, etc.) with ink" is from 1727. Related: Inked; inks; inking.
ink-well (n.): also inkwell, 1854, from ink (n.) + well (n.). A schoolroom implement, so called because it sat down in the surface of a desk in contrast to an ink-stand.
inkhorn (n.): late 14c., "small portable vessel (originally made of horn) for holding ink," from ink (n.) + horn (n.). Used attributively from 1540s ("Soche are your Ynkehorne termes," John Bale) as an adjective for things (especially vocabulary) supposed to be beloved by scribblers, pedants, and bookworms. An Old English word for the thing was blæchorn.
inkling (n.): c. 1400, apparently from the gerund of the Middle English verb inclen "utter in an undertone, hint at, hint" (mid-14c.), which is of unknown origin; perhaps it is related to Old English inca "doubt, suspicion, question, scruple." However the earliest record of the word is as a nyngkiling; and Middle English Dictionary offers that this is not a misdivision of an inkling but rather suggests the word is a nasalized variant of nikking "a hint, slight indication," gerundive of the Middle English verb nikken "to mark (a text) for correction" (mid-15c.), from nik (n.) "a notch, tally" (see nick (n.)).
inky (adj.): "as black as ink," 1590s, from ink (n.) + -y (2). Related: Inkily; inkiness.
inlaid (adj.): 1590s, "embedded in (something)," from in + laid, past participle of lay (v.). In old slang (c. 1700) it meant "full of money, living at ease."
inland (adj.): "of or pertaining to interior parts of a country," 1550s, from in + land (n.). The noun meaning "interior parts of a country (remote from the sea or borders)" is attested from 1570s. Meaning "confined to a country" (as opposed to foreign) is from 1540s. In Middle English and Old English the same compound meant "land immediately around the mansion of an estate, land in the lord's own occupation (as opposed to land occupied by tenants)." Related: Inlander.
inlandish (adj.): 1650s, "produced at home, domestic, native," from inland in the "domestic, not foreign" sense + -ish. Also "characteristic of inland regions" (1849). Old English had inlendisc, inlende "native, indigenous."
inlapidate (v.): "turn to stone" (trans.), 1620s, from in- (2) "in, into" + verb from Latin lapis (genitive lapidis) "stone" (see lapideous). Related: Inlapidated; inlapidating.
inlay (v.): 1590s, "insert in or into," from in (adv.) + lay (v.). As a noun, "that which is inlaid" (especially for ornamental effect), from 1650s. Related: Inlaid.
inlet (n.): "narrow opening into a coast, arm of the sea," 1570s, said by old sources to be originally a Kentish term; a special use of Middle English inlate "passage or opening by which an enclosed place may be entered" (c. 1300), from inleten "to let in" (early 13c.), from in + let (v.).
inlier (n.): 1859, from in (adv.) on model of outlier.
inlighten (v.): former alternative form of enlighten (q.v.). Related: Inlightened; inlightening.
inline (adj.): also in-line, 1913 of printing, 1921 of engines, 1958 of computers, by 1989 of roller skates; from in + line (n.).
inly (adv.): Old English inlice "internally, inwardly; sincerely, heartily;" see in + -ly (2).
inmate (n.): 1580s, "one allowed to live in a house rented by another" (usually for a consideration), from in (adj.) "inside" + mate (n.) "companion." OED suggests the first element is perhaps originally inn. Sense of "one confined to an institution" is first attested 1834.
inmost (adj.): 16c. respelling of Middle English innemest, from Old English innemest "furthest within, remotest from the boundary;" see in + -most.
inn (n.): Old English inn "lodging, dwelling, house," probably from inne (adv.) "inside, within" (see in). Meaning "public house with lodging" is perhaps by c. 1200, certainly by c. 1400. Meaning "lodging house or residence for students" is attested from early 13c. in Anglo-Latin, now obsolete except in names of buildings that were so used (such as Inns of Court, mid-15c.).
innards (n.): "entrails of an animal," 1825, innerds, dialectal variant of inwards "the bowels" (c. 1300); see inward. Compare inmeat "edible entrails of animals" (c. 1400); Old English innoð "entrails, stomach."
innate (adj.): early 15c., "existing from birth," from Late Latin innatus "inborn, native, natural" (source also of French inné, Spanish and Italian innato), past participle of innasci "to be born in, originate in," from in- "in" (see in- (2)) + nasci "to be born" (Old Latin gnasci; see genus). Opposed to acquired. Related: Innately; innateness.
inner (adj.): c. 1400, from Old English inra, comparative of inne (adv.) "inside" (see in (adv.)). Similar formation in Old High German innaro, German inner. The original order of comparison was in/inner/inmost; the evolution has been unusual for a comparative, and inner has not been used with than since Middle English.

Inner man "the soul" is from late Old English. The Quaker inner light is attested by that name from 1833. Inner tube in the pneumatic tire sense is from 1894. Inner city is attested from 1690s; as a euphemism for "urban poverty and crime," from 1963.
innermost (adj.): mid-14c., from inner + -most. In the same sense innerest is from c. 1200. The older word is inmost. Innermore also existed in Middle English.
innervate (v.): "stimulate through the nerves," 1870, a back-formation from innervation "sending of a stimulus through the nerves" (1828), which is perhaps modeled on French innervation; see in- (2) "in" + nerve (n.) + -ate. Related: Innervated. Earlier in English the same word (but from the other in-) meant "to lose feeling or sensation" (1848), and, as an adjective, "without feeling" (1737). Innervation in psychology is from 1880, translated from German Innervationsgefühl.
innie (n.): in reference to navels, by 1972, from in (adj.) + -ie.
inning (n.): Old English innung "a taking in, a putting in," gerundive of innian "get within, put or bring in; lodge; include; fill up, restore," from inn (adv.) "in" (see in). Meaning "a team's turn in action in a game" first recorded 1735, usually plural in cricket, singular in baseball.
innkeeper (n.): 1540s, from inn + keeper.
innocence (n.): mid-14c., "freedom from guilt or moral wrong," from Old French inocence "innocence; purity, chastity" (12c., Modern French innocence), from Latin innocentia "blamelessness, uprightness, integrity," from innocens "harmless; blameless; disinterested" (see innocent). Meaning "lacking in guile or artifice," as of childhood, is from late 14c. Meaning "freedom from legal wrong" is from 1550s.
innocense (n.): alternative spelling of innocence.
innocent (adj.): mid-14c., "doing no evil; free from sin, guilt, or moral wrong," from Old French inocent "harmless; not guilty; pure" (12c.), from Latin innocentem (nominative innocens) "not guilty, blameless; harmless; disinterested," from in- "not" (see in- (1)) + nocentem (nominative nocens), present participle of nocere "to harm," from *nok-s-, suffixed form of PIE root *nek- (1) "death" (see necro-).

Meaning "free from guilt of a specific crime or charge" is from late 14c., as is the meaning "with childlike simplicity or artlessness." Humorous sense "free, devoid of" is from 1706. The noun meaning "person who is innocent of sin or evil, artless or simple person" is from c. 1200, especially a young child (who presumably has not yet sinned actively). The Holy Innocents (early 14c.) were the young children slain by Herod after the birth of Jesus (Matt. ii:16), hence Innocents day (Dec. 28).

Indo-European words for "innocent" are generally negative compound of the word for "guilty." An exception is the Germanic group represented by Gothic swikns (also "pure, chaste"), Old Norse sykn "free from guilt, innocent" (especially as a law term), Old English swicn "clearance from a charge," also "cleansing," but these are of uncertain origin.
innocently (adv.): c. 1400, from innocent (adj.) + -ly (2).
innocuous (adj.): 1590s, from Latin innocuus "harmless; innocent; inoffensive," from in- "not" (see in- (1)) + nocuus "hurtful," from root of nocere "to injure, harm," from *nok-s-, suffixed form of PIE root *nek- (1) "death" (see necro-). Related: Innocuously; innocuousness.
innominable (adj.): "unnameable," late 14c., from Old French innominable, from Late Latin innominabilis "that cannot be named," from in- "not, opposite of" (see in- (1)) + *nominabilis, from Latin nominalis "pertaining to a name or names," from nomen (genitive nominis) "name"(see name (n.)). In jocular use, innominables = "trousers" (1827; see inexpressible).