insense (v.) Look up insense at Dictionary.com
"teach, instruct, cause (someone) to understand," c. 1400, ensense, from Old French ensenser "to enlighten, to bring to sense," from en- "in" (see in- (2)) + sens (see sense (n.)). "From 17th c. app. only dialectal (chiefly northern), or in writers under dialectal influence" [OED].
insensibility (n.) Look up insensibility at Dictionary.com
late 14c., "absence of physical sensation, numbness," from Late Latin insensibilitas, from insensibilis "that cannot be felt" (see insensible). Meaning "quality of being imperceptible" is from 1630s. Meaning "absence of moral feeling, indifference" is from 1690s.
insensible (adj.) Look up insensible at Dictionary.com
c. 1400, "lacking the power to feel with the senses, numb, dazed" (now rare in this meaning), from Late Latin insensibilis "that cannot be felt," from in- "not" (see in- (1)) + sensibilis "having feeling: perceptible by the senses" (see sensible). Meaning "void of feeling, not susceptible to emotion or passion" is from 1610s. Meaning "incapable of being felt or perceived by the senses or the mind, so small or slight as to be imperceptible" is from late 14c. Compare insensate.
insensibly (adv.) Look up insensibly at Dictionary.com
"so as not to be felt or perceived," early 15c.; see insensible + -ly (2).
insensitive (adj.) Look up insensitive at Dictionary.com
c. 1600, "having little or no reaction to what is perceived by one's senses," from in- (1) "not, opposite of" + sensitive. For sense, see insensate. From 1834 as "having little or no mental or moral sensitiveness;" meaning "without consideration for the feelings of others" attested by 1974. Related: Insensitively.
insensuous (adj.) Look up insensuous at Dictionary.com
"not affecting the senses," 1851, from in- (1) "not, opposite of" + sensuous. Related: Insensuously; insensuousness.
inseparability (n.) Look up inseparability at Dictionary.com
1620s, from Late Latin inseparabilitas "inseparableness," from Latin inseparabilis "that cannot be separated," from in- "not, opposite of" (see in- (1)) + separabilis, from separare (see separate (v.)).
inseparable (adj.) Look up inseparable at Dictionary.com
mid-14c., from Latin inseparabilis "that cannot be separated," from in- "not, opposite of" (see in- (1)) + separabilis, from separare "to pull apart" (see separate (v.)). Related: Inseparably.
insert (v.) Look up insert at Dictionary.com
"to set in, put or place in," 1520s, from Latin insertus, past participle of inserere "to graft, implant," from in- "in" (see in- (2)) + serere "attach, join; arrange, line up," from PIE *ser- (3) "to line up" (see series). Middle English had inseren "to set in place, to graft, to introduce (into the mind)" (late 14c.), directly from the Latin verb. Related: Inserted; inserting.
insert (n.) Look up insert at Dictionary.com
"something inserted," 1893, especially a paper, etc., placed in among the pages of a newspaper, magazine, etc., from insert (v.).
insertion (n.) Look up insertion at Dictionary.com
1590s, "act of putting in," from French insertion (16c.) or directly from Late Latin insertionem (nominative insertio) "a putting in," noun of action from past participle stem of Latin inserere "to graft, implant" (see insert (v.)). Meaning "that which is inserted" attested from 1620s.
inset (n.) Look up inset at Dictionary.com
1550s, "influx of water; place where water flows in," from in (prep.) + set (n.2). The later word in a sense "that which is set in" ("extra pages of a book, etc.," 1875; "small map in the border of a larger one," 1881) probably are a separate formation. In Old English insetan (Old Northumbrian insetta) meant "an institution," literally "a setting in," and perhaps a loan-translation of the source of institution. Similar formation in German einsetzen "to use, employ; institute, begin; install."
inshallah (interj.) Look up inshallah at Dictionary.com
1818, phonetic spelling of Arabic in sha Allah "if Allah wills (it)."
inshore (adj.) Look up inshore at Dictionary.com
also in-shore, "near the shore," 1701, from in (prep.) + shore (n.). As an adverb from 1737.
inside (n.) Look up inside at Dictionary.com
late 14c., ynneside "interior part (of the body)," compound of in (prep.) + side (n.). General sense "inner side or part (of anything)" is from c. 1500.

The adjective sense "being on the inside" is from 1610s, from the noun. It began to be used in slang c. 1900 in reference to the supposed real facts or situation that only an insider would know. Inside man is from 1911 (originally in reference to workers used by management to sniff out union activity); inside job "robbery, espionage, etc., committed by or with the help of a resident or servant of a place" is attested by 1887, American English (also, late 19c., early 20c., "indoors work"). The figurative inside track "advantage" (1854) however is a metaphor from horse racing (1830); inside lanes are shorter than the outer ones on a curved track. Adverbial use in American English inside of (in reference to time) is from 1839.
inside-out (adj.) Look up inside-out at Dictionary.com
"with the in side being out," c. 1600, from inside (n.) + out (prep.).
insider (n.) Look up insider at Dictionary.com
"one in possession of special information by virtue of being within some organization," 1848, from inside (n.) + -er (1). Originally in reference to the stock markets.
insidious (adj.) Look up insidious at Dictionary.com
1540s, from Middle French insidieux "insidious" (15c.) or directly from Latin insidiosus "deceitful, cunning, artful, treacherous," from insidiae (plural) "plot, snare, ambush," from insidere "sit on, occupy," from in- "in" (see in- (2)) + sedere "to sit" (see sedentary). Figurative, usually with a suggestion of lying in wait and the intent to entrap. Related: Insidiously; insidiousness.
insight (n.) Look up insight at Dictionary.com
c. 1200, innsihht, "sight with the 'eyes' of the mind, mental vision, understanding from within," from in (prep.) + sight (n.). But the meaning often seems to be felt as "sight into" (something else), and so the sense shifted to "penetrating understanding into character or hidden nature" (1580s). Similar formation in Dutch inzigt, German einsicht, Danish indsigt.
insightful (adj.) Look up insightful at Dictionary.com
"with penetrating understanding into character or hidden nature," 1881, from insight + -ful. Some earlier words in the same sense were insighted (c. 1600), inseeing "having insight" (1590s). Related: Insightfully; insightfulness.
insignia (n.) Look up insignia at Dictionary.com
1640s, from Latin insignia, neuter plural of insigne "badge of honor or office, mark, proof, sign, token," from in- "in" (see in- (2)) + signum "mark" (see sign (n.)). The classically correct singular is insigne.
insignificance (n.) Look up insignificance at Dictionary.com
1690s, from insignificant + -ance. Earlier was insignificancy (1650s).
insignificant (adj.) Look up insignificant at Dictionary.com
1650s, "without meaning," also "answering to no purpose," from in- (1) "not, opposite of" + significant. From 1748 as "small in size." Related: Insignificantly.
insincere (adj.) Look up insincere at Dictionary.com
1620s (implied in insincerely), from Latin insincerus "spoiled, corrupted; not genuine, not pure, adulterated," from in- "not" (see in- (1)) + sincerus "genuine, candid" (see sincere). Related: Insincerely.
insincerity (n.) Look up insincerity at Dictionary.com
1540s, from in- (1) "not, opposite of" + sincerity, or else from Latin insincerus "not genuine, not pure; spoiled, corrupted" (see insincere).
insinuate (v.) Look up insinuate at Dictionary.com
1520s, "to covertly and subtly introduce into the mind or heart" (trans.), from Latin insinuatus, past participle of insinuare "to thrust in, push in, make a way; creep in, intrude, bring in by windings and curvings, wind one's way into," from in- "in" (see in- (2)) + sinuare "to wind, bend, curve," from sinus "a curve, winding" (see sinus).

Intransitive meaning "hint obliquely" is from 1560s. Meaning "maneuver (someone or something) into some desired position or condition" is from 1570s. Physical or literal sense of "to introduce tortuously or indirectly" is from 1640s. Related: Insinuated; insinuating.
insinuating (adj.) Look up insinuating at Dictionary.com
"wheedling, ingratiating," 1590s, present-participle adjective from insinuate (v.). Related: Insinuatingly.
insinuation (n.) Look up insinuation at Dictionary.com
1520s, "act of making an indirect suggestion;" 1530s, "that which is indirectly suggested," from Middle French insinuation (16c.) or directly from Latin insinuationem (nominative insinuatio) "entrance through a narrow way; an ingratiating oneself," noun of action from past participle stem of insinuare "creep in, intrude, wind one's way into" (see insinuate).
insipid (adj.) Look up insipid at Dictionary.com
1610s, "without taste or perceptible flavor," from Middle French insipide "insipid" (16c.), from Late Latin inspidus "tasteless," from in- "not" (see in- (1)) + Latin sapidus "tasty," from sapere "have a taste" (also "be wise;" see sapient). Figurative meaning "uninteresting, dull" first recorded in English 1640s, probably from Medieval Latin or the Romance languages, where it was a secondary sense.
In ye coach ... went Mrs. Barlow, the King's mistress and mother to ye Duke of Monmouth, a browne, beautifull, bold, but insipid creature. [John Evelyn, diary, Aug. 18, 1649]
Related: Insipidly.
insipidity (n.) Look up insipidity at Dictionary.com
c. 1600, from insipid + -ity.
insipience (n.) Look up insipience at Dictionary.com
early 15c., "lack of wisdom, foolishness," from Old French insipience (15c.) or directly from Latin insipientia "folly, unwisdom," from insipientem "unwise, foolish" (see insipient).
insipient (adj.) Look up insipient at Dictionary.com
"foolish," mid-15c., from Latin insipientem (nominative insipiens) "unwise, foolish," from in- "not" (see in- (1)) + sapientem (see sapient). "Now mostly, or wholly, disused to avoid confusion with incipient" [OED].
insist (v.) Look up insist at Dictionary.com
1580s, from French insister (14c.) or directly from Latin insistere "take a stand, stand on, stand still; follow, pursue; insist, press vigorously, urge, dwell upon," from in- "upon" (see in- (2)) + sistere "take a stand" (see assist (v.)). Perhaps in some cases a back-formation from insistence. Related: Insisted; insisting.
insistence (n.) Look up insistence at Dictionary.com
mid-15c., "persistence, urgency," from Old French insister "to insist" (14c.) and directly from Latin insistere (see insist) + -ence.
insistent (adj.) Look up insistent at Dictionary.com
1620s, "standing on something," from Latin insistentem (nominative insistens), present participle of insistere "stand on," also "urge, insist," from in- "upon" (see in- (2)) + sistere "take a stand" (see assist (v.)). Meaning "persistent, urgent, demanding attention" is from 1868. Related: Insistently.
insobriety (n.) Look up insobriety at Dictionary.com
1610s, from in- (1) "not, opposite of" + sobriety.
insociability (n.) Look up insociability at Dictionary.com
1740, from insociable "unsociable" (1580s), from in- (1) "not, opposite of" + sociable.
insolate (v.) Look up insolate at Dictionary.com
"expose to the rays of the sun," 1620s, from Latin insolatus, past participle of insolare "place in the sun, expose to the sun," from in- "in" (see in- (2)) + sol "sun" (see Sol). Related: Insolated; insolating.
insolation (n.) Look up insolation at Dictionary.com
"exposure to the sun's rays," 1610s, from French insolation (16c.), from Latin insolationem (nominative insolatio), noun of action from past participle stem of insolare "place in the sun, expose to the sun," from in- "in" (see in- (2)) + sol "sun" (see Sol).
insole (n.) Look up insole at Dictionary.com
"inner sole of a shoe or boot," 1838, from in + sole.
insolence (n.) Look up insolence at Dictionary.com
late 14c., from Latin insolentia "unusualness, strangeness; excess, immoderation; haughtiness, arrogance," from insolentem "unusual; arrogant" (see insolent).
insolent (adj.) Look up insolent at Dictionary.com
late 14c., "contemptuous, arrogant, showing haughty disregard of others," from Latin insolentem (nominative insolens) "arrogant, immoderate," also "unaccustomed, unwonted," literally "unusual, unfamiliar," from in- "not, opposite of" (see in- (1)) + solentem, present participle of solere "be accustomed, be used to; cohabit with," from Proto-Italic *sol-e-.

This is of uncertain origin. An old guess connects it to the source of Latin sodalis "close companion," and suescere "become used to," but de Vaan rejects this on phonetic grounds. Another guess connects it to the source of Latin solum "ground," with a possible sense shift from "inhabit" to "be accustomed to." Or it might be from PIE root *sel- (1) "human settlement" (cognates: Old Church Slavonic selo "courtyard, village," Russian selo "village," Old English sele, Old High German sal "hall, house"). Meaning "contemptuous of rightful authority" is from 1670s. Related: Insolently.
Insolent is now chiefly used of language that is intentionally and grossly rude, defiant, or rebellious. Where it applies to conduct, the conduct includes language as the most offensive thing. [Century Dictionary, 1902]
insolubility (n.) Look up insolubility at Dictionary.com
1754, "incapability of dissolving in a liquid," 1791, from Late Latin insolubilitas, from Latin insolubilis "that cannot be loosened" (see insoluble). Earlier in a sense "that cannot be dissolved" (of marriage), 1610s. The meaning "that cannot be solved" (1722) probably is a separate formation from insoluble.
insoluble (adj.) Look up insoluble at Dictionary.com
late 14c., "indestructible, unable to be loosened," also figuratively, of problems, etc., "incapable of being solved or explained," from Old French insoluble or directly from Latin insolubilis "that cannot be loosened," from in- "not" (see in- (1)) + solubilis "that can be loosened" (see soluble).
It was a tacit conviction of the learned during the Middle Ages that no such thing as an insoluble question existed. There might be matters that presented serious difficulties, but if you could lay them before the right man -- some Arab in Spain, for instance, omniscient by reason of studies into the details of which it was better not to inquire -- he would give you a conclusive answer. The real trouble was only to find your man. [Gertrude Bell, "The Desert and the Sown," 1907]
Meaning "incapable of being dissolved in a liquid" is from 1713.
insolvable (adj.) Look up insolvable at Dictionary.com
1650s, from French insolvable (15c.), from in- "not, opposite of" (see in- (2)) + solvable (see solvable).
insolvency (n.) Look up insolvency at Dictionary.com
1660s, from insolvent (q.v.) + -cy. Insolvence (1793) is rare.
insolvent (adj.) Look up insolvent at Dictionary.com
1590s, "unable to pay one's debts," from in- (1) "not" + Latin solventem "paying" (see solvent). Originally of one who was not a trader; only traders could become bankrupt.
insomnia (n.) Look up insomnia at Dictionary.com
"chronic inability to sleep," 1620s, insomnie, from Latin insomnia "want of sleep, sleeplessness," from insomnis "sleepless," from in- "not" (see in- (1)) + somnus "sleep" (see Somnus). The re-Latinized form is from 1758.
insomniac Look up insomniac at Dictionary.com
1877 (adj.); 1879 (n.), from insomnia. Earlier was insomnious (1650s).
insomuch (adv.) Look up insomuch at Dictionary.com
late 14c. as a phrase; tending to be run together from 16c.; see in (adv.) + so + much, and compare inasmuch.