indiscernible (adj.) Look up indiscernible at Dictionary.com
1630s, from in- (1) "not, opposite of" + discernible. Related: Indiscernibly; indiscernibility.
indiscipline (n.) Look up indiscipline at Dictionary.com
1783, from in- (1) "not, opposite of" + discipline (n.). Indisciplined as a past participle adjective is attested from c.1400.
indiscreet (adj.) Look up indiscreet at Dictionary.com
"imprudent, not discrete" (early 15c.) and indiscrete "not containing distinct parts" (c.1600) are both from Latin indiscretus "unseparated; indistinguishable, not known apart," the former via an Old French or Medieval Latin secondary sense. From in- "not" (see in- (1)) + discreet. Related: Indiscreetly; indiscreetness.
indiscrete (adj.) Look up indiscrete at Dictionary.com
see indiscreet. Related: Indiscretely.
indiscretion (n.) Look up indiscretion at Dictionary.com
mid-14c., "want of discretion," from Old French indiscrécion "foolishness, imprudence" (12c.), from Late Latin indiscretionem (nominative indiscretio) "lack of discernment," from in- (see in- (1)) + discretionem (see discretion). Meaning "indiscreet act" is from c.1600.
indiscriminate (adj.) Look up indiscriminate at Dictionary.com
1640s, from in- (1) "not, opposite of" + discriminate (adj.).
indiscriminately (adv.) Look up indiscriminately at Dictionary.com
1650s, from indiscriminate + -ly (2).
indispensability (n.) Look up indispensability at Dictionary.com
1640s, from indispensable + -ity.
indispensable (adj.) Look up indispensable at Dictionary.com
1530s, from Medieval Latin indispensabilis, from in- "not, opposite of" (see in- (1)) + dispensabilis (see dispensable). Related: Indispensably.
indisposed (adj.) Look up indisposed at Dictionary.com
c.1400, "unprepared;" early 15c., "not in order," from in- (1) "not" + disposed; or else from Late Latin indispositus "without order, confused." Mid-15c. as "diseased;" modern sense of "not very well" is from 1590s. A verb indispose is attested from 1650s but is perhaps a back-formation of this.
indisposition (n.) Look up indisposition at Dictionary.com
early 15c., "unfavorable influence" (in astrology); also in Middle English, "ill health, disorder of the mind or body; unfavorable disposition, hostility; inclination to evil; wickedness; public disorder, lawlessness," from in- (1) "not, opposite of" + disposition.
indisputable (adj.) Look up indisputable at Dictionary.com
1550s, from Late Latin indisputabilis, from in- "not, opposite of, without" (see in- (1)) + disputabilis (see dispute). Related: Indisputably.
indissolubility (n.) Look up indissolubility at Dictionary.com
1670s, from indissoluble + -ity.
indissoluble (adj.) Look up indissoluble at Dictionary.com
mid-15c. (implied in indissolubly), from Latin indissolubilis "that cannot be dissolved," from in- "not, opposite of" (see in- (1)) + dissolubilis, from dis- + solubilis (see soluble).
indistinct (adj.) Look up indistinct at Dictionary.com
c.1400 (implied in indistinctly "equally, alike"), from Latin indistinctus "not distinct, confused," from in- "not, opposite of" (see in- (1)) + distinctus (see distinct). Related: Indistinctly; indistinctness.
indistinguishable (adj.) Look up indistinguishable at Dictionary.com
c.1600, from in- (1) "not, opposite of" + distinguishable. Related: Indistinguishably.
indite (v.) Look up indite at Dictionary.com
late 14c., "put down in writing," from Old French enditer, from Vulgar Latin *indictare, from Latin in- "in, into, on, upon" (see in- (2)) + dictare “to declare” (see dictate). The same word as indict but retaining a French form. Related: Indited; inditing.
inditement (n.) Look up inditement at Dictionary.com
1560s, "action of writing prose or verse," from indite + -ment.
individual (adj.) Look up individual at Dictionary.com
early 15c., "one and indivisible" (with reference to the Trinity), from Medieval Latin individualis, from Latin individuus "indivisible," from in- "not, opposite of" (see in- (1)) + dividuus "divisible," from dividere "divide" (see divide). Not common before c.1600 and the 15c. usage might be isolated. Sense of "single, separate" is 1610s; meaning "intended for one person" is from 1889.
individual (n.) Look up individual at Dictionary.com
"single object or thing," c.1600, from individual (adj.). Colloquial sense of "person" is attested from 1742. Latin individuum meant "an atom, indivisible particle;" in Middle English individuum was used in sense of "individual member of a species" from early 15c.
individualism (n.) Look up individualism at Dictionary.com
"self-centered feeling," 1827, from individual + -ism. As a social philosophy (opposed to communism and socialism) first attested 1851 in writings of J.S. Mill.
A majority can never replace the individual. ... Just as a hundred fools do not make one wise man, a heroic decision is not likely to come from a hundred cowards. [Adolf Hitler, "Mein Kampf," 1933]
individualist (n.) Look up individualist at Dictionary.com
1840, from individual + -ist. Related: Individualistic.
individuality (n.) Look up individuality at Dictionary.com
"the aggregate of one's idiosyncrasies," 1610s, from individual + -ity. Meaning "fact of existing as an individual" is from 1650s.
individualize (v.) Look up individualize at Dictionary.com
1650s, "to point out individually;" see individual + -ize. From 1837 as "to make individual." Related: Individualized; individualizing.
individually (adv.) Look up individually at Dictionary.com
1590s, "indivisibly," from individual + -ly (2). Meaning "as individuals" is from 1640s.
individuate (v.) Look up individuate at Dictionary.com
1610s, from Medieval Latin individuatus, past participle of individuare, from Latin individuus (see individual). Related: Individuated; individuating.
individuation (n.) Look up individuation at Dictionary.com
1620s, from Medieval Latin individuationem, noun of action from individuare, from individuus (see individual). Psychological sense is from 1909.
indivisibility (n.) Look up indivisibility at Dictionary.com
1640s, from indivisible + -ity.
indivisible (adj.) Look up indivisible at Dictionary.com
early 15c., from Middle French indivisible and directly from Late Latin indivisibilis, from in- "not, opposite of" (see in- (1)) + divisibilis (see divisible).
Indo-European Look up Indo-European at Dictionary.com
1814, coined by physician, physicist and Egyptologist Thomas Young (1773-1829) and first used in an article in the "Quarterly Review," from Indo-, comb. form of Greek Indos "India" + European. "Common to India and Europe," specifically in reference to the group of related languages and to the race or races characterized by their use. The alternative Indo-Germanic (1835) was coined in German 1823 (indogermanisch), based on the two peoples at the extremes of the geographic area covered by the languages, before Celtic was realized also to be an Indo-European language. After this was proved, many German scholars switched to Indo-European as more accurate, but Indo-Germanic continued in use (popularized by the titles of major works) and the predominance of German scholarship in this field made it the popular term in England, too, through the 19c. See also Aryan.
Indochina Look up Indochina at Dictionary.com
1886, from Indo-, comb. form of Greek Indos "India" + China. Name proposed early 19c. by Scottish poet and orientalist John Leyden, who lived and worked in India from 1803 till his death at 35 in 1811.
indoctrinate (v.) Look up indoctrinate at Dictionary.com
1620s, "to teach," from in- (2) "in" + Latin doctrina "teaching" (see doctrine). Meaning "to imbue with an idea or opinion" first recorded 1832. Related: Indoctrinated; indoctrinating. The earlier verb was indoctrine (c.1500).
indoctrination (n.) Look up indoctrination at Dictionary.com
1640s, noun of action from indoctrinate.
indolence (n.) Look up indolence at Dictionary.com
c.1600, "insensitivity to pain," from French indolence (16c.), from Latin indolentia "freedom from pain, insensibility," noun of action from indolentem (nominative indolens) "insensitive to pain," used by Jerome to render Greek apelgekos in Ephesians; from Latin in- "not, opposite of, without" (see in- (1)) + dolentem (nominative dolens) "grieving," present participle of dolere "suffer pain." Sense of "laziness" (1710) is from notion of "avoiding trouble" (compare taking pains).
indolent (adj.) Look up indolent at Dictionary.com
1660s, "painless," from Late Latin indolentem (see indolence). Sense of "living easily" is 1710, from French indolent. Related: Indolently.
indomitable (adj.) Look up indomitable at Dictionary.com
1630s, from Late Latin indomitabilis "untameable," from in- "not, opposite of, without" (see in- (1)) + *domitabilis, from Latin domitare, frequentative of domare "to tame" (see tame). Related: Indomitably.
Indonesian Look up Indonesian at Dictionary.com
1850, from Indonesia, from Indo-, comb. form of Greek Indos "India" (see India) + nesos "island" (see Chersonese). Formerly called Indian Archipelago or East Indies Islands (see Indies).
indoor (adj.) Look up indoor at Dictionary.com
1711, from within door (opposed to outdoor); the form indoors is first attested 1799 in George Washington's writings.
indorsement (n.) Look up indorsement at Dictionary.com
see endorsement.
indrawn (adj.) Look up indrawn at Dictionary.com
also in-drawn, 1751, from in (adv.) + past tense of draw (v.). Middle English had indrawing "action of drawing in" (late 14c.). The plain verb indraw is rare, late 19c., and might be a back-formation.
indri (n.) Look up indri at Dictionary.com
1839, European name for the babakoto, a lemur-like arboreal primate of Madagascar (Indris Lichanotus); the common story since late 19c. is that the name was given in error by French naturalist Pierre Sonnerat (1748-1814), c.1780, from mistaken use of Malagasy indry! "look! See!" Evidently this was what his native guides said when they spotted the creature and called his attention to it.
However, as Hacking (1981) pointed out, Sonnerat was far too familiar with indris -- he described and figured them in detail, and apparently kept at least one in captivity -- for this story to be plausible. Furthermore, endrina is actually recorded as a native name for the indri (Cousins, 1885), and indri could easily be a variant of this name. Although the word endrina is first recorded in Malagasy only in 1835, there is no evidence that it could be a back-formation from the French indri (Hacking, 1981), and it seems implausible that the Malagasy would adopt an erroneous French name for an animal they were them selves familiar with. [Dunkel, Alexander R., et al., "Giant rabbits, marmosets, and British comedies: etymology of lemur names, part 1," in "Lemur News," vol. 16, 2011-2012, p.67]
indubitable (adj.) Look up indubitable at Dictionary.com
mid-15c., from Latin indubitabilis "that cannot be doubted," from in- "not, opposite of" (see in- (1)) + dubitabilis "doubtful," from dubitare "hesitate, doubt" (see doubt).
indubitably (adv.) Look up indubitably at Dictionary.com
late 15c., from indubitable + -ly (2).
induce (v.) Look up induce at Dictionary.com
late 14c., "to lead by persuasions or other influences," from Latin inducere "lead into, bring in, introduce, conduct, persuade," from in- "into, in, on, upon" (see in- (2)) + ducere "to lead" (see duke (n.)). Meaning "to bring about," of concrete situations, etc., is from early 15c.; sense of "to infer by reasoning" is from 1560s. Electro-magnetic sense first recorded 1777. Related: Induced; inducing.
inducement (n.) Look up inducement at Dictionary.com
1590s, "that which induces," from induce + -ment.
inducive (adj.) Look up inducive at Dictionary.com
1610s, from induce + -ive.
induct (v.) Look up induct at Dictionary.com
late 14c., from Latin inductus, past participle of inducere "to lead" (see induce). Originally of church offices; sense of "bring into military service" is 1934 in American English. Related: Inducted; inducting.
inductance (n.) Look up inductance at Dictionary.com
1886, from induct + -ance.
inductee (n.) Look up inductee at Dictionary.com
1941, American English, from induct + -ee.
induction (n.) Look up induction at Dictionary.com
late 14c., "advancement toward the grace of God;" also (c.1400) "formal installation of a clergyman," from Old French induction (14c.) or directly from Latin inductionem (nominative inductio) "a leading in, introduction," noun of action from past participle stem of inducere "to lead" (see induce).

As a term in logic (early 15c.) it is from Cicero's use of inductio to translate Greek epagoge "leading to" in Aristotle. Induction starts with known instances and arrives at generalizations; deduction starts from the general principle and arrives at some individual fact. As a term of science, c.1800; military service sense is from 1934, American English.