Online Etymology Dictionary

in-service (adj.): also inservice, 1928, from in (prep.) + service (n.).
in-store (adj.): also instore, 1954, from in (prep.) + store (n.). In Middle English, instore was a verb meaning "to restore, renew," from Latin instaurare.
in-transit (adj.): 1907, from commercial verbal phrase in transit "on the way or passage, while passing from one to another" (1819, earlier in Latin form in transitu), from in + transit (n.).
inability (n.): mid-15c., inhabilite, "disqualification for office," from in- (1) + ability. Earlier was unability "incapability; incompetence" (late 14c.). General sense "state of being unable" is recorded by c. 1500.
inable (v.): obsolete form of enable.
inaccessible (adj.): early 15c., from Middle French inaccessible (14c.), from Late Latin inaccessibilis "unapproachable," from in- "not" (see in- (1)) + accessibilis "approachable" (see accessible). Related: Inaccessibly; inaccessibility. Earlier in same sense was unaccessible (c. 1400).
inaccuracy (n.): 1701, "quality or condition of being inaccurate," from inaccurate + -cy. As "an instance of being inaccurate, that which is inaccurate," 1704.
inaccurate (adj.): 1690s, from in- (1) "not" + accurate. Unaccurate is attested from 1670s. Related: Inaccurately (1660s).
inaction (n.): 1705, from in- (1) "not, opposite of" + action (n.). Perhaps modeled on French Inaction.
inactive (adj.): 1640s, from in- (1) "not, opposite of" + active. Perhaps a back-formation from Inactivity.
inactivity (n.): 1640s, from in- (1) "not, opposite of" + activity. Phrase masterly inactivity attested by 1791.
inadequacy (n.): 1764, from inadequate + -cy. Related: Inadequacies.
inadequate (adj.): 1670s; see in- (1) "not, opposite of" + adequate. Related: Inadequately.
inadmissible (adj.): 1744, from in- (1) "not, opposite of" + admissible. Perhaps modeled on French inadmissible. Related: Inadmissibility.
inadvertence (n.): mid-15c., from Old French inadvertance "thoughtlessness, heedlessness" (14c.), from Scholastic Latin inadvertentia, from in- "not" (see in- (1)) + advertentia, from Latin advertere "to direct one's attention to," literally "to turn toward" (see advertise).
inadvertent (adj.): 1650s, "not properly attentive" (of persons), a back-formation from inadvertence. Meaning "unconscious, unintentional" (of actions) is from 1724.
inadvertently (adv.): 1670s, from inadvertent + -ly (2). "Inattentively, carelessly," hence "unintentionally."
inadvisability (n.): 1839, from inadvisable + -ity.
inadvisable (adj.): 1819, from in- (1) "not, opposite of" + advisable.
inalienable (adj.): "that cannot be given up," 1640s, from in- (1) "not, opposite of" + alienable (adj.). Perhaps from French inaliénable (16c.). Related: Inalienably; Inalienability.
inamorata (n.): "female lover, woman with whom one is in love," 1650s, from Italian innamorata "mistress, sweetheart," noun use of fem. of innamorato, past participle of innamorare "to fall in love," from in "in" (from Latin, see in) + amore "love," from Latin amor (see Amy).
inamorato (n.): "male lover; man who is in love," 1590s, from Italian innamorato, noun use of masc. past participle of innamorare "to fall in love" (see inamorata).
inane (adj.): 1660s, "empty, void," from Latin inanis or else a back-formation from inanity (q.v.). Sense of "silly, empty-headed" is from 1819. Related: Inanely. Bailey's Dictionary (1731) has inaniloquent "given to empty talk."
inanimate (adj.): early 15c., "without vital force,having lost life," from Late Latin inanimatus "lifeless," from in- "not" (see in- (1)) + animatus (see animation). The Latin word closest corresponding in form and sense is inanimalis. Meaning "lacking vivacity, without spirit, dull" is from 1734. Inanimate as a verb meant "infuse with life or vigor" (17c.), from the other in- (see in- (2)).
inanition (n.): in medicine, "exhaustion from lack of nourishment," c. 1400, "pathological draining or depletion of blood, humors, or bodily fluids," from Old French inanition (14c.) and directly from Latin inanitionem (nominative inanitio) "emptiness," noun of action from past participle stem of inanire "to empty," from inanis "empty, void; worthless, useless," a word of uncertain origin.
inanity (n.): c. 1600, "emptiness, hollowness," literal and figurative, from French inanité (14c.) or directly from Latin inanitas "emptiness, empty space," figuratively "worthlessness," noun of quality from inanis "empty, void; worthless, useless," a word of uncertain origin. De Vaan writes that "The chronology of attestations suggests that 'empty, devoid of' is older than 'hollow'." Meaning "silliness, want of intelligence" is from 1753.
inappetence (n.): "failure of appetite," 1690s, from French inappétence (16c.), from assimilated form of in- "not, opposite of" (see in- (1)) + appétence "desire" (for food); see appetence. Related: Inappetency (1610s).
inapplicable (adj.): 1650s, from in- (1) "not, opposite of" + applicable. Related: Inapplicably; inapplicability.
inapposite (adj.): "not pertinent, not fit or suitable," 1620s (implied in inappositely), from in- (1) "not, opposite of" + apposite.
inappreciable (adj.): 1773, "too inconsiderable to matter;" 1787, "that cannot be sufficiently appreciated," from in- (1) "not, opposite of" + appreciable. Perhaps modeled on French inappreciable. Related: Inappreciably.
inapprehensible (adj.): 1640s, from in- (1) "not, opposite of" + apprehensible.
inappropriate (adj.): 1791, from in- (1) "not, opposite of" + appropriate (adj.). Related: Inappropriately; inappropriateness. Unappropriate is from 1742.
inapt (adj.): "ill-suited to the purpose or occasion," 1734, from in- (1) "not, opposite of" + apt. Related: Inaptly; inaptness. Compare inept.
inaptitude (n.): 1610s, from in- (1) "not, opposite of" + aptitude. The Frenchified version is ineptitude.
inarticulate (adj.): c. 1600, "not clear or intelligible" (of speech); "not jointed or hinged, not composed of segments connected by joints" (in biology), from Late Latin inarticulatus "not articulate, not distinct," from in- "not" (see in- (1)) + articulatus, past participle of articulare "to separate into joints; to utter distinctly" (see articulation). Of persons, "not able to speak clearly," 1754. Related: Inarticulately; inarticulateness; inarticulable.
inartistic (adj.): "not conformable to the rules or principles of art" [Century Dictionary], 1836, from in- (1) "not" + artistic. Inartistical is attested from 1849. Related: Inartistically.
inasmuch (adv.): contraction of phrase in as much "to such a degree," which is first attested c. 1300 as in als mikel, a Northern form. Contracted to in asmuch, then, beginning 14c. and especially since 17c., to one word. Meaning "in view of the fact" (followed by as) is from late 14c.
inattention (n.): 1710, from in- (1) "not, opposite of" + attention. Perhaps modeled on French inattention.
inattentive (adj.): 1650s, from in- (1) "not, opposite of" + attentive. Related: Inattentively; inattentiveness.
inaudibility (n.): 1808, from inaudible + -ity.
inaudible (adj.): c. 1600, "unable to be heard," from Late Latin inaudibilis "inaudible," from in- "not" (see in- (1)) + audibilis (see audible). Used in Middle English in the sense "unfit to be heard" (mid-15c.). Related: Inaudibly. Classical Latin had inauditus "unheard, unheard of."
inaugural (adj.): 1680s, from French inaugural (17c.), from inaugurer "to inaugurate" (14c.), from Latin inaugurare "to inaugurate" (see inauguration). The noun meaning "an inaugural address" is recorded from 1832, American English.
inaugurate (v.): "induct into office by formal ceremony," c. 1600, a back-formation from inauguration (q.v.) and also from Latin inauguratus, past participle of inaugurare. The etymological sense is "make a formal beginning or induction into office with suitable ceremonies" (which in ancient Rome included especially the taking of auguries). Related: Inaugurated; inaugurating; inaugurator.
inauguration (n.): 1560s, from French inauguration "installation, consecration," and directly from Late Latin inaugurationem (nominative inauguratio) "consecration," presumably originally "installment under good omens;" noun of action from past participle stem of inaugurare "take omens from the flight of birds; consecrate or install when omens are favorable," from in- "on, in" (see in- (2)) + augurare "to act as an augur, predict" (see augur (n.)).
INAUGURATIO was in general the ceremony by which the augurs obtained, or endeavoured to obtain, the sanction of the gods to something which had been decreed by man; in particular, however, it was the ceremony by which things or persons were consecrated to the gods .... If the signs observed by the inaugurating priest were thought favourable, the decree of men had the sanction of the gods, and the inauguratio was completed. [William Smith (ed.), "Dictionary of Greek and Roman Antiquities," 1842]
inauspicious (adj.): 1590s, from in- (1) "not, opposite of" + auspicious. Related: Inauspiciously; inauspiciousness. The Latin word was inauspicatus "without auspices; with bad auspices," which had a brief career in English as inauspicate (17c.).
inauthentic (adj.): 1783, from in- (1) "not, opposite of" + authentic. Related: Inauthentically.
inboard (adv.): "within the hull or interior of a ship," 1830, from in (adv.) + board (n.2).
inborn (adj.): Old English inboren "native to a place, indigenous, aboriginal," from in (prep.) "within" + boren "brought forth" (see born). Of personal qualities, "innate, implanted by nature," 1510s.
inbound (adj.): 1857, "homeward," from in + bound (adj.2). Originally of ships.
inbox (n.): by 1984 in electronic mail sense, from in + mailbox (n.). Compare in-basket, in reference to office mail systems, by 1940; in-tray (1917).