Online Etymology Dictionary

immature (adj.): 1540s, "untimely, premature," from Latin immaturus "untimely, unripe," from assimilated form of in- "not, opposite of" (see in- (1)) + maturus "ripe, timely, early" (see mature (v.)). In 16c., usually in reference to early death; main modern sense of "not fully developed" first recorded 1640s. In reference to mentalities or behaviors not considered age-appropriate, from 1920. Related: Immaturely.
immaturity (n.): 1530s, "untimeliness," from Latin immaturitatem (nominative immaturitas) "unripeness," from immaturus "unripe, untimely" (see immature). Meaning "lack of maturity" attested from c. 1600.
immeasurable (adj.): late 14c., immesurable, from im- + measurable. It could alternate with immensurable. Related: Immeasurably.
immediacy (n.): c. 1600, from immediate + -cy. Middle English had immediacioun "close connection, proximity" (mid-15c.).
immediate (adj.): late 14c., "intervening, interposed;" early 15c., "with nothing interposed; direct," also with reference to time, "without delay, instant," from Old French immediat (14c.), from Late Latin immediatus "without anything between," from assimilated form of in- "not, opposite of" (see in- (1)) + mediatus "in the middle" (see mediate).
immediately (adv.): "without intervening time or space, directly," early 15c., from immediate + -ly (2).
immediatism (n.): "advocacy of immediate action" (originally with reference to abolition of slavery in the U.S.), 1834, from immediate + -ism.
immemorable (adj.): "not memorable," 1550s, from Latin immemorabilis "not worth mentioning; silent," from assimilated form of in- "not" (see in- (1)) + memorabilis (see memorable). In English it occasionally has been used to mean "old beyond memory," but that sense is best left to immemorial.
immemorial (adj.): c. 1600, from French immémorial "old beyond memory" (16c.), from Medieval Latin immemorialis, from assimilated form of in- "not, opposite of" (see in- (1)) + Latin memorialis of or belonging to memory" (see memorial (n.)). Something immemorial is ancient beyond memory; something immemorable is not worth remembering. Latin immemor meant "unmindful, forgetful, heedless."
immense (adj.): "great beyond measure," early 15c., from Old French immense (mid-14c.), from Latin immensus "immeasurable, boundless," also used figuratively, from assimilated form of in- "not, opposite of" (see in- (1)) + mensus "measured," past participle of metiri "to measure" (see measure (v.)). A vogue word in 18c., and mocked as such:
For instance, a long while every thing was immense great and immense little, immense handsome and immense ugly. Miss Tippet from the cloisters, could not drink tea with Master Parchment at the White Conduit-house, unless it was an immense fine day, yet probably it might rain so immense, there was no going without a coach. ["Town and Country Magazine" (in "Annual Register" for 1772)]
immensely (adv.): 1650s, from immense + -ly (2).
immensity (n.): mid-15c., "vastness; infinity," from Middle French immensité (14c.) or directly from Latin immensitatem (nominative immensitas) "immeasurableness," noun of quality from immensus "immeasurable, boundless" (see immense). Immenseness is from c. 1600.
immensurable (adj.): "immeasurable," c. 1500, from Old French immensurable, from Late Latin immensurabilis, from mensurabilis "able to be measured" (see mensurable).
immerge (v.): 1620s (trans.), "immerse, plunge into (a fluid)," from Latin immergere "to dip, plunge into" (see immersion). Intransitive sense from 1706. Rare; the usual verb is immerse. Related: Immerged; immerging.
immerse (v.): "to plunge into (a fluid)," early 15c. (implied in immersed), from Latin immersus, past participle of immergere "to plunge in, dip into, sink, submerge" (see immersion). Figuratively, of study, work, passion, etc., from 1660s. Related: Immersed; immersing; immersive.
immersion (n.): c. 1500, from Late Latin immersionem (nominative immersio), noun of action from past participle stem of immergere "to plunge in, dip into, sink, submerge," from assimilated form of in- "into, in, on, upon" (see in- (2)) + Latin mergere "plunge, dip" (see merge). Meaning "absorption in some interest or situation" is from 1640s. As a method of teaching a foreign language, 1965, trademarked by the Berlitz company.
immigrant (n.): "one who immigrates," 1792, American English, perhaps based on French immigrant, from Latin immigrantem (nominative immigrans), present participle of immigrare "to remove, go into, move in" (see immigrate). Emigrant is older. First used in English in Jeremy Belknap's history of New Hampshire, and he generally is credited with having coined it.
There is another deviation from the strict letter of the English dictionaries; which is found extremely convenient in our discourses on population. From the verb migro are derived emigrate and IMMIGRATE; with the same propriety as from mergo are derived emerge and IMMERGE. Accordingly the verb IMMIGRATE and the nouns IMMIGRANT and IMMIGRATION are used without scruple in some parts of this volume. [Preface to vol. III of "The History of New Hampshire," Belknap, 1792]
As an adjective from 1805.
immigrate (v.): "to pass into a place as a new inhabitant or resident," especially "to move to a country where one is not a native, for the purpose of settling permanently there," 1620s, from Latin immigratum, past participle of imigrare "to remove, go into, move in," from assimilated form of in- "into, in, on, upon" (see in- (2)) + migrare "to move" (see migration). Related: Immigrated; immigrating.
immigration (n.): 1650s, noun of action from immigrate. As "immigrants collectively," from 1852. As short for "immigration authorities," from 1966.
imminence (n.): c. 1600, from Late Latin imminentia, from Latin imminentem (see imminent).
imminent (adj.): 1520s, from Middle French imminent (14c.) and directly from Latin imminentem (nominative imminens) "overhanging; impending," present participle of imminere "to overhang, lean towards," hence "be near to," also "threaten, menace, impend, be at hand, be about to happen," from assimilated form of in- "into, in, on, upon" (see in- (2)) + -minere "jut out," which is related to mons "hill" (see mount (n.1)). Related: Imminently.
immiscible (adj.): "incapable of being mixed" (as oil and water are), 1670s, from assimilated form of in- "not, opposite of" (see in- (1)) + miscible, from Latin miscere "to mix" (see mix (v.)).
immitigable (adj.): 1570s, from Latin immitigabilis, from assimilated form of in- "not" (see in- (1)) + mitigabilis, from past participle stem of mitigare "make mild or gentle" (see mitigate). Related: Immitigably.
immobile (adj.): mid-14c., originally of property; by c. 1400 "steadfast, unmovable" (of faith, etc.), from Old French immoble "immovable, fixed, motionless" (13c., Modern French immeuble), from Latin immobilis "immovable" (also, figuratively, "hard-hearted"), from assimilated form of in- "not, opposite of" (see in- (1)) + mobilis (see mobile (adj.)). Related: Immobilism "policy of extreme conservatism" (1853).
immobilise (adj.): chiefly British English spelling of immobilize (q.v.); for suffix, see -ize. Related: immobilisation; immobilised; immobilising.
immobility (n.): early 15c., from Middle French immobilité (14c.) or directly from Latin immobilitatem (nominative immobilitas) "immovableness," noun of quality from Latin immobilis "immovable" (see immobile).
immobilization (n.): 1846, noun of action from immobilize.
immobilize (v.): "render immobile," 1843, from immobile + -ize. Perhaps modeled on French immobiliser (1835). Related: Immobilized; immobilizing.
immoderate (adj.): "excessive, extreme, lacking moderation," late 14c., from Latin immoderatus "boundless, immeasurable," figuratively "unrestrained, excessive," from assimilated form of in- "not, opposite of" (see in- (1)) + moderatus "restrained" (see moderate (adj.)). Related: Immoderately.
immoderation (n.): early 15c., from Latin immoderationem (nominative immoderatio) "want of moderation, excess," from immoderatus "unrestrained, excessive" (see immoderate).
immodest (adj.): 1560s, "arrogant, impudent, not modest about one's pretentions," from Latin immodestus "unrestrained, excessive," from assimilated form of in- "not, opposite of" (see in- (1)) + modestus (see modest). Meaning "indecent, lewd, not modest in person or utterance" is from 1580s. Related: immodestly.
immodesty (n.): 1590s, "lewdness, indecency;" c. 1600, "arrogance," from Latin immodestia "intemperate conduct," from immodestus "unrestrained, excessive" (see immodest).
immolate (v.): 1540s, "to sacrifice, kill as a victim," from Latin immolatus, past participle of immolare "to sacrifice," originally "to sprinkle with sacrificial meal," from assimilated form of in- "into, in, on, upon" (see in- (2)) + mola (salsa) "(sacrificial) meal," related to molere "to grind" (see mallet). Related: Immolated; immolating.
immolation (n.): early 15c., "a sacrificing, sacrificial killing" (originally especially with reference to Christ), from Old French immolacion "offering, sacrifice" (13c.) or directly from Latin immolationem (nominative immolatio) "a sacrificing," noun of action from past participle stem of immolare "to sacrifice" (see immolate).
immoral (adj.): 1650s, "not consistent with moral law or standards, ethically wrong," from assimilated form of in- (1) "not" + moral (adj.). In legal language it tends to mean merely "contrary to common good or reasonable order." Related: Immorally.
immorality (n.): 1560s, from assimilated form of in- (1) "not, opposite of" + morality.
immortal (adj.): late 14c., "deathless," from Latin immortalis "deathless, undying" (of gods), "imperishable, endless" (of fame, love, work, etc.), from assimilated form of in- "not, opposite of" (see in- (1)) + mortalis "mortal" (see mortal (adj.)). In reference to fame, literature, etc., "unceasing, destined to endure forever, never to be forgotten, lasting a long time," attested from early 15c. (also in classical Latin). As a noun, "an immortal being," from 1680s.
immortalise (v.): chiefly British English spelling of immortalize (q.v.); for suffix, see -ize. Related: immortalisation; immortalised; immortalising.
immortality (n.): mid-14c., "deathlessness," from Old French immortalité (13c.) and directly from Latin immortalitatem (nominative immortalitas) "deathlessness, endless life," also "imperishable fame," from immortalis "undying" (see immortal). Of fame, etc., "quality of being permanent," early 15c.
immortalization (n.): c. 1600, noun of action or state from immortalize.
immortalize (v.): 1560s, "bestow lasting fame upon, exempt from oblivion," from immortal + -ize. Perhaps modeled on Middle French immortaliser. The literal sense "endow with immortality" is from 1630s in English. Related: Immortalized; immortalizing.
immortelle (n.): "flower which preserves its shape and color after being dried" (also known as an everlasting), 1832, from French fem. of immortel "undying," from Latin immortalis (see immortal).
immovability (n.): late 14c., immoevablete, "quality of being unchanging," from immovable + -ity.
immovable (adj.): late 14c., literal and figurative, also sometimes in Middle English immevable, from assimilated form of in- (1) "not, opposite of" + movable. Related: Immovably.
immune (adj.): mid-15c., "free, exempt" (from taxes, tithes, sin, etc.), from Latin immunis "exempt from public service, untaxed; unburdened, not tributary," from assimilated form of in- "not, opposite of" (see in- (1)) + munis "performing services" (compare municipal), from PIE *moi-n-es-, suffixed form of root *mei- (1) "to change" (see mutable). Specific modern medical sense of "exempt (from a disease)," typically because of inoculation, is from 1881, a back-formation from immunity. Immune system attested by 1917.
immunity (n.): late 14c., "exemption from service or obligation," from Old French immunité "privilege; immunity from attack, inviolability" (14c.) and directly from Latin immunitatem (nominative immunitas) "exemption from performing public service or charge, privilege," from immunis "exempt, free," (see immune (adj.)). Medical sense of "protection from disease" is from 1879, from French or German.
immunization (n.): 1892, noun of action from immunize.
immunize (v.): 1889, in a translation of a German article, from immune + -ize. Related: Immunized; immunizing.
immunodeficiency (n.): 1969, from comb. form of immune + deficiency.
immunology (n.): by 1906, a hybrid from immune + -ology. Related: Immunological; immunologist.