Online Etymology Dictionary

inditement (n.): 1560s, "action of writing prose or verse," from indite + -ment. Perhaps modeled on French enditement (12c.).
indium (n.): metallic element, 1864, Modern Latin, from indicum "indigo" (see indigo) + chemical name element -ium. So called for its spectral lines. Ferdinand Reich (1799-1882), professor of physics at Freiberg, isolated it while analyzing local zinc ores in 1863 and identified it as a new element by the two dark blue lines in its spectrum, which did not correspond to any known element. The discovery had to be observed by his assistant, Theodor Richter, because Reich was color-blind.
individual (adj.): early 15c., "one and indivisible, inseparable" (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). Original sense now obsolete; the word was not common before c. 1600 and the 15c. example might be an outlier. Sense of "single, separate, of but one person or thing" is from 1610s; meaning "intended for one person" is from 1889.
individual (n.): "single object or thing," c. 1600, from individual (adj.). Meaning "a single human being" (as opposed to a group, etc.) is from 1640s. Colloquial sense of "person" is attested from 1742. Latin individuum as a noun meant "an atom, indivisible particle," and in Middle English individuum was used in sense of "individual member of a species" (early 15c.).
individualism (n.): "quality of being distinct or individual, individuality," 1815, from individual + -ism. As the name of a social philosophy favoring non-interference of government in lives of individuals (opposed to communism and socialism) first attested 1851 in writings of J.S. Mill.
individualist (n.): 1839, "egoist, free-thinker," from individual + -ist, and compare individualism. Related: Individualistic.
individuality (n.): 1610s, "the aggregate of one's idiosyncrasies," from individual + -ity, or from Medieval Latin individualitas. Meaning "condition of existing as an individual" is from 1650s.
individualization (n.): also individualisation, noun of action from individualize. Attested in 1746 but rare in English before 1820s, in which use probably it is a borrowing from French or German.
individualize (v.): 1630s, "to make individual, stamp with individual character;" 1650s, "to point out individually, to note separately as individuals;" see individual + -ize. Related: Individualized; individualizing.
individually (adv.): 1590s, "indivisibly," from individual + -ly (2). Meaning "as individuals" is from 1640s.
individuate (v.): 1610s, from Medieval Latin individuatus, past participle of individuare "make individual," from Latin individuus "individual" (see individual (adj.)). Perhaps modeled on obsolete French individuer. Related: Individuated; individuating.
individuation (n.): 1620s, from Medieval Latin individuationem (nominative individuatio), noun of action from past participle stem of individuare "to make individual," from Latin individuus "individual" (see individual (adj.)). Psychological sense is from 1909.
indivisibility (n.): 1640s, from indivisible + -ity. Perhaps modeled on French indivisibilité.
indivisible (adj.): early 15c., from Old French indivisible (14c.) and directly from Late Latin indivisibilis "not divisible," from in- "not, opposite of" (see in- (1)) + divisibilis (see divisible). Related: Indivisibly.
Indo-: word-forming element meaning "of or pertaining to India" (and some other place), from Greek Indo-, from Indos "India" (see India).
Indo-China: also Indochina, "Further India, the region between India and China," 1815, from Indo- "India" + China. The name was said to have been proposed by Scottish poet and orientalist John Leyden, who lived and worked in India from 1803 till his death at 35 in 1811. French Indo-Chine is attested from 1813, but the source credits it to Leyden. The inappropriateness of the name was noticed from the start. Related: Indo-Chinese (1814).
Indo-European: 1814, coined by English polymath Thomas Young (1773-1829) and first used in an article in the "Quarterly Review," from Indo- + 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 in 1823 (indogermanisch), based on the two peoples then thought to be at the extremes of the geographic area covered by the languages, but this was 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. Indo-Aryan (1850) seems to have been used only of the Aryans of India. Indo-European also was used in reference to trade between Europe and India or European colonial enterprises in India (1813).
Indo-Germanic (adj.): 1835, from German; see Indo-European.
Indo-Iranian (adj.): 1838, from Indo- + Iranian.
Indo-Pacific (adj.): 1851, in biology, from Indo- + Pacific.
indocile (adj.): c. 1600, from French indocile (15c.) or directly from Latin indocilis, from in- "not, opposite of" (see in- (1)) + docilis (see docile).
indoctrinate (v.): formerly also endoctrinate, 1620s, "to teach," formed as if from Latin (but there seems to have been no word *indoctrinare), perhaps modeled on French endoctriner or extended from earlier (now obsolete) verb indoctrine, endoctrine, "to instruct" (mid-15c.); see in- (2) "in" + doctrine + -ate (2)). Meaning "to imbue with an idea or opinion" first recorded 1832. Related: Indoctrinated; indoctrinating.
indoctrination (n.): 1640s, "instruction," noun of action from indoctrinate. In reference to imbuing with opinions or ideology, from 1865.
indolence (n.): c. 1600, "indifference to pain," from French indolence (16c.) or directly from Late Latin indolentia "freedom from pain, insensibility," noun of state from Latin indolentem (nominative indolens) "insensitive to pain," from in- "not, opposite of, without" (see in- (1)) + dolentem (nominative dolens) "grieving," present participle of dolere "suffer pain, grieve" (see doleful). Originally of prisoners under torture, etc. The intermediate sense "state of rest or ease neither pleasant nor painful" (1650s) is now obsolete as well; main modern sense of "laziness, love of ease" (1710) perhaps reflects the notion of avoiding trouble (compare taking pains "working hard, striving (to do)").
The Castle hight of Indolence,
And its false Luxury;
Where for a little Time, alas!
We liv'd right jollity.

[Thomson, "The Castle of Indolence," 1748]
indolent (adj.): 1660s, "causing no pain, painless," from French indolent (16c.) or directly from Late Latin indolentem (see indolence). Sense of "living easily, slothful," is 1710, a sense perhaps developed in French. Related: Indolently.
indomitable (adj.): 1630s, "that cannot be tamed or subdued," 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 (adj.)). In reference to persons or personal qualities, "unyielding, persistent, resolute," by 1830. Related: Indomitably.
Indonesia: "the East Indies," 1850, from Indo- "India" + Greek nesos "island" (see Chersonese) + -ia. Formerly called Indian Archipelago or East Indies Islands (see Indies). Related: Indonesian "of or from the East Indies" (1850).
indoor (adj.): also in-door, 1711, opposed to outdoor, contracted from within door; the form indoors is attested from 1759 (within-doors is from 1750); as an adverb from 1801.
indorse (v.): see endorse. Indorser was old slang for "a sodomite" (1785).
indorsement (n.): see endorsement.
Indra: Vedic thunder god, from Sanskrit Indrah, a word of uncertain origin.
indrawn (adj.): also in-drawn, 1751, from in (adv.) + past tense of draw (v.). Middle English had indraw "bring about, cause" (late 14c.), "pull inward" (early 15c.). Also compare indraft "inward flow, a drawing in" (1590s). The modern verb indraw (1871) is rare and might be a back-formation.
indri (n.): 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!" this being 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]
indubious (adj.): "certain, not doubtful," 1620s, from Latin indubius "not doubtful," from in- "not, opposite of" (see in- (1)) + dubius "vacillating, fluctuating," figuratively "wavering in opinion, doubting" (see dubious). Related: Indubiously.
indubitable (adj.): mid-15c., "too plain to admit of doubt," from Latin indubitabilis "that cannot be doubted," from in- "not, opposite of" (see in- (1)) + dubitabilis "doubtful," from dubitare "hesitate, doubt" (see doubt (v.)).
indubitably (adv.): "unquestionably, without a doubt," late 15c., from indubitable + -ly (2).
induce (v.): formerly also enduce, late 14c., "to lead by persuasions or other influences," from Latin inducere "lead into, bring in, introduce, conduct; persuade; suppose, imagine," from in- "into, in, on, upon" (see in- (2)) + ducere "to lead" (see duke (n.)). Meaning "to bring about" in any way (in reference to a trance, a fever, 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.): 1590s, "that which induces," from induce + -ment.
inducive (adj.): "tending to induce," 1610s, from induce + -ive.
induct (v.): late 14c., "introduce, initiate, especially into office or employment," from Latin inductus, past participle of inducere "to lead into, introduce" (see induce). Originally of church offices; sense of "draft into military service" is 1917 in American English. Related: Inducted; inducting.
inductance (n.): 1879, in electricity, from induct + -ance.
inductee (n.): 1941, American English, from induct + -ee.
induction (n.): 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, admission," 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 in physics, in reference to electrical influence, 1801; military service sense is from 1934, American English. Related: Inductional.
inductive (adj.): early 15c., "bringing on, inducing," from Old French inductif or directly from Late Latin inductivus "serving to induce or infer," from induct-, past participle stem of Latin inducere (see induce). As a term in logic, "based on induction" (q.v.), from 1764. Related: Inductively.
inductor (n.): 1650s, "one who initiates," agent noun from Latin stem of induce. Classical Latin inductor meant "one who stirs up, an instigator." Electromagnetic senses are from 1837.
indulge (v.): formerly also endulge, 1630s, "to grant as a favor;" 1650s, "to treat with unearned favor" (in reference both to persons and desires), a back-formation from indulgence (q.v.), or else from Latin indulgere "be complaisant, be indulgent, yield; give oneself up to;" probably a compound verb with first element in- "in," but the second element is obscure. Related: Indulged; indulging; indulgingly.
indulgence (n.): mid-14c., in the Church sense, "a freeing from temporal punishment for sin, remission from punishment for sin that remains due after absolution," from Old French indulgence or directly from Latin indulgentia "complaisance, a yielding; fondness, tenderness, affection; remission," from indulgentem (nominative indulgens) "indulgent, kind, tender, fond," present participle of indulgere "be kind; yield, concede, be complaisant; give oneself up to, be addicted," a word of uncertain origin; perhaps from in- "in" + a derivative of PIE root *dlegh- "to engage oneself," the source of play (v.) and plight (v.).

Sense of "leniency, forbearance of restraint or control of another, gratification of desire or humor" is attested from late 14c. That of "yielding to one's inclinations" (technically self-indulgence) in English is from 1630s. In British history, Indulgence also refers to grants of certain liberties to Nonconformists under Charles II and James II, as special favors rather than legal rights. The sale of indulgences in the original Church sense was done at times merely to raise money and was widely considered corrupt; the one in 1517 helped to spark the Protestant revolt in Germany.
indulgent (adj.): "lenient, willing to overlook faults," often in a bad sense, "too lenient," c. 1500, from Latin indulgentem (nominative indulgens) "kind, tender, fond," present participle of indulgere "be kind, be complaisant, yield" (see indulgence). Related: Indulgently.
indurate (v.): 1590s (transitive) "make hard;" 1620s (intransitive) "grow harder," from Latin induratus, past participle of indurare "to make hard, harden" (see endure). Related: Indurated.
indurate (adj.): "hardened, made hard," early 15c., from Latin induratus, past participle of indurare "to make hard, harden" (see endure).