Online Etymology Dictionary

insatiability (n.): 1650s, from Late Latin insatiabilitas, from insatiabilis (see insatiable).
insatiable (adj.): early 15c., insaciable, from Old French insaciable (13c.), or directly from Late Latin insatiabilis "not to be satisfied," from in- "not, opposite of" (see in- (1)) + satiabilis, from satiare (see satiate). Related: Insatiably.
insatiate (adj.): mid-15c., insaciate, from Latin insatiatus "unsatisfied," from in- "not, opposite of" (see in- (1)) + satiatus, past participle of satiare (see satiate).
inscribe (v.): 1550s (form inscriven is from late 14c.), from Latin inscribere "to write in or on," (see inscription). Meaning "to dedicate (by means of an inscription)" is from 1640s. Related: Inscribed; inscribing.
inscription (n.): late 14c., from Latin inscriptionem (nominative inscriptio) "a writing upon, inscription," noun of action from past participle stem of inscribere "inscribe, to write on or in anything," from in- "in" (see in- (2)) + scribere "to write" (see script).
inscrutability (n.): 1650s, from inscrutable + -ity.
inscrutable (adj.): c.1500, from Late Latin inscrutabilis, from in- "not, opposite of" (see in- (1)) + scrutabilis, from scrutari "examine, ransack" (see scrutiny). Related: Inscrutably.
insect (n.): c.1600, from Latin (animal) insectum "(animal) with a notched or divided body," literally "cut into," from neuter past participle of insectare "to cut into, to cut up," from in- "into" (see in- (2)) + secare "to cut" (see section (n.)). Pliny's loan-translation of Greek entomon "insect" (see entomology), which was Aristotle's term for this class of life, in reference to their "notched" bodies.

First in English in 1601 in Holland's translation of Pliny. Translations of Aristotle's term also form the usual word for "insect" in Welsh (trychfil, from trychu "cut" + mil "animal"), Serbo-Croatian (zareznik, from rezati "cut"), Russian (nasekomoe, from sekat "cut"), etc.
insecticide (n.): "substance which kills insects," 1865, from insect + -cide.
insectivore (n.): 1863, from French insectivore (1817), from Latin insectivorus, from comb. form of insectum (see insect) + vorare "devour, swallow" (see voracity).
insecure (adj.): 1640s, "unsafe," from Medieval Latin insecurus, from in- "not" (see in- (1)) + Latin securus (see secure). Psychological sense dates from 1935; insecurity in this sense dates from 1917. Related: Insecurely.
insecurity (n.): 1640s, from Medieval Latin insecuritas, from insecurus (see insecure). Specific psychological sense is by 1917.
inseminate (v.): 1620s, "to cast as seed," from Latin inseminatus, past participle of inseminare "to sow, implant," from in- "in" (see in- (2)) + semen (genitive semenis) "seed." Meaning "to impregnate with semen" is attested from 1923. Related: Inseminated; inseminating.
insemination (n.): 1650s, "action of sowing," noun of action from inseminate. Meaning "infusion of semen" is from 1860.
insensate (adj.): 1510s, from Late Latin insensatus "irrational, foolish," from Latin in- "not" (see in- (1)) + sensatus "gifted with sense" (see sensate). Insensate means "not capable of feeling sensation," often "inanimate;" insensible means "lacking the power to feel with the senses," hence, often, "unconscious;" insensitive means "having little or no reaction to what is perceived by one's senses," often "tactless."
insense (v.): "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.)). Restricted to Northern English dialect from 17c.
insensibility (n.): late 14c., from Late Latin insensibilitas, from Latin insensibilis (see insensible).
insensible (adj.): c.1400, "lacking the power to feel with the senses," from Latin insensibilis "that cannot be felt," from in- "not" (see in- (1)) + sensibilis (see sensible). Also sometimes in Middle English "incapable of being felt or perceived by the senses" (early 15c.). Meaning "unconscious" is attested from early 15c. See insensate.
insensibly (adv.): early 15c.; see insensible + -ly (2).
insensitive (adj.): 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. Meaning "without consideration for the feelings of others" attested by 1975. Related: Insensitively.
inseparability (n.): 1620s, from Late Latin inseparabilitas, from Latin inseparabilis (see inseparable).
inseparable (adj.): mid-14c., from Latin inseparabilis "that cannot be separated," from in- "not, opposite of" (see in- (1)) + separabilis, from separare (see separate (v.)). Related: Inseparably.
insert (v.): "to set in, put or place in," 1520s, from insert, past participle of Middle English inseren "to set in place, to graft, to introduce (into the mind)" (late 14c.), from Latin inserere "to put in, implant," from in- "in" (see in- (2)) + serere "join together" (see series). Related: Inserted; inserting. The noun meaning "something inserted" is from 1893.
insertion (n.): 1590s, "act of putting in," from Late Latin insertionem (nominative insertio), noun of action from past participle stem of inserere (see insert). Meaning "that which is inserted" attested from 1620s.
inservice (adj.): also in-service, 1928, from in + service.
inset (n.): 1550s, "influx of water, place where water flows in," from in + set. Meaning "extra pages of a book, etc." is from 1875; that of "small map in the border of a larger one" is from 1881.
inshallah: 1857, phonetic spelling of Arabic in sha Allah "if Allah wills (it)."
inside (n.): late 14c., ynneside "interior of the body," compound of in (adv.) + side (n.). The adjective is 1610s, from the noun. 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"). Inside track "advantage" is metaphoric because those lanes are shorter on a curved track. Inside of, in reference to time, is from 1839.
inside-out (adj.): "with the in side being out," c.1600, from inside + out (adv.).
insider (n.): "one in possession of special information by virtue of being within some organization," 1848, from inside + -er (1). Originally in reference to the stock markets.
insidious (adj.): 1540s, from Middle French insidieux (15c.) or directly from Latin insidiosus "deceitful, cunning, artful," from insidiae (plural) "plot, snare, ambush," from insidere "sit on, occupy," from in- "in" (see in- (2)) + sedere "to sit" (see sedentary). Related: Insidiously; insidiousness.
insight (n.): c.1200, innsihht, "sight with the eyes of the mind," mental vision, understanding," from in + sight. Sense shaded into "penetrating understanding into character or hidden nature" (1580s).
insightful (adj.): 1881, from insight + -ful. Related: Insightfully; insightfulness.
insignia (n.): 1640s, from Latin insignia, neuter plural of insigne "badge, mark," from in- "in" (see in- (2)) + signum "mark" (see sign). Singular is insigne.
insignificance (n.): 1690s, from insignificant + -ance. Related: Insignificancy (1650s).
insignificant (adj.): 1650s, from in- (1) "not, opposite of" + significant. Related: Insignificantly.
insincere (adj.): 1620s (implied in insincerely), from Latin insincerus "not genuine, not pure, adulterated," from in- "not" (see in- (1)) + sincerus (see sincere).
insincerity (n.): 1540s, from Latin insincerus (see insincere) + -ity.
insinuate (v.): 1520s, from Latin insinuatus, past participle of insinuare "to throw 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." Sense of "to introduce tortuously or indirectly" is from 1640s. Related: Insinuated; insinuating; insinuatingly.
insinuation (n.): 1520s, from Latin insinuationem (nominative insinuatio) "entrance through a narrow way; an ingratiating oneself," noun of action from past participle stem of insinuare (see insinuate).
insipid (adj.): 1610s, "without taste or perceptible flavor," from French insipide (16c.), from Late Latin inspidus "tasteless," from Latin in- "not" (see in- (1)) + sapidus "tasty," from sapere "have a taste" (also "be wise;" see sapient). Figurative meaning "uninteresting, dull" first recorded 1640s, but it was also a secondary sense in Medieval Latin.
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.): c.1600, from insipid + -ity.
insipience (n.): early 15c., "lack of wisdom, foolishness," from Old French insipience, from Latin insipientia "folly," from insipientem (see insipient).
insipient (adj.): "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.): 1580s, from Latin insistere "persist, dwell upon, stand upon," from in- "upon" (see in- (2)) + sistere "take a stand" (see assist). Perhaps in some cases a back-formation from insistence. Related: Insisted; insisting.
insistence (n.): mid-15c., from Middle French insister (see insist) + -ence.
insistent (adj.): 1620s, "standing on something," from Latin insistentem (nominative insistens), present participle of insistere (see insist). Meaning "dwelling firmly on something asserted" is from 1868. Related: Insistently.
insobriety (n.): 1610s, from in- (1) "not, opposite of" + sobriety.
insolate (v.): "to expose to the rays of the sun," 1620s, from Latin insolatus, past participle of insolare, from in- "in" (see in- (2)) + sol "sun" (see Sol). Related: Insolated; insolation.
insole (n.): 1850s, from in + sole.