inbred (adj.) Look up inbred at Dictionary.com
1590s, "native, produced within," also "inherent by nature," from in + bred. The genetic sense is attested from 1892 (see inbreeding).
inbreeding (n.) Look up inbreeding at Dictionary.com
"breeding of animals from the same parentage," c. 1842, from in + verbal noun from breed (v.). The older term for "to breed from animals of the same parentage" was to breed in and in (1765). The verb inbreed is attested from 1590s in the sense "produce within" (intransitive).
Inc. Look up Inc. at Dictionary.com
U.S. abbreviation of Incorporated in company names (equivalent of British Ltd.), first attested 1904.
Inca (n.) Look up Inca at Dictionary.com
1590s, from Spanish Inga (1520s), from Quechea Inca, literally "lord, king." Technically only of the high Inca, but it was used widely among the Incas for "man of royal blood." Related: Incan.
incalculable (adj.) Look up incalculable at Dictionary.com
1772, from in- (1) "not, opposite of" + calculable "that can be counted" (see calculate). Related: Incalculably; incalculability.
incandescence (n.) Look up incandescence at Dictionary.com
1650s, figurative, "state of being 'inflamed,' " from French incandescence, from incandescent (see incandescent). Literal use from 1794.
incandescent (adj.) Look up incandescent at Dictionary.com
1794, from French incandescent (18c.) or directly from Latin incandescentem (nominative incandescens), present participle of incandescere "become warm, glow, kindle," from in- "within" (see in- (2)) + candescere "begin to glow, become white," inceptive of candere "to glow, to shine" (see candle). In reference to electric light, from 1881. The verb incandesce (1874) is perhaps a back-formation.
incantation (n.) Look up incantation at Dictionary.com
late 14c., from Old French incantacion "spell, exorcism" (13c.), from Late Latin incantationem (nominative incantatio) "art of enchanting," noun of action from past participle stem of incantare "to bewitch, charm, cast a spell upon, chant magic over, sing spells" (see enchantment).
incapable (adj.) Look up incapable at Dictionary.com
1590s, from Middle French incapable (16c.) and directly from Medieval Latin incapabilis "incapable," from in- "not" (see in- (1)) + capabilis "receptive; able to grasp or hold" (see capable). Related: Incapably; incapability.
incapacitate (v.) Look up incapacitate at Dictionary.com
1650s in a legal sense; 1660s in general use, "deprive of natural power," from incapacity + -ate. Related: Incapacitated; incapacitating.
incapacitation (n.) Look up incapacitation at Dictionary.com
1741, noun of action from incapacitate.
incapacity (n.) Look up incapacity at Dictionary.com
1610s, "lack of ability, powerlessness," from French incapacité (16c.), from Medieval Latin incapacitatem (nominative incapacitas), from Late Latin incapax (genitive incapacis) "incapable," from in- "not" (see in- (1)) + Latin capax "capable," literally "able to hold much," from capere "to take" (see capable). As a legal term (1640s), "lack of qualification," referring to inability to take, receive, or deal with in some way.
incarcerate (v.) Look up incarcerate at Dictionary.com
"imprison, shut up in jail," 1550s, a back-formation from incarceration (q.v.), or else from Medieval Latin incarceratus, past participle of incarcerare "to imprison." Related: Incarcerated; incarcerating.
incarceration (n.) Look up incarceration at Dictionary.com
"fact of being imprisoned," 1530s, from Medieval Latin incarcerationem (nominative incarceratio), noun of action from past participle stem of incarcerare "to imprison," from in- "in" (see in- (2)) + carcer "prison, an enclosed space," from Proto-Italic *kar-kr(o)-, of uncertain origin.
It seems best to connect carcer with other IE words for 'circle, round object', such as [Latin] curvus, [Greek] κιρκος 'ring', [Old Norse] hringr, although not all of these have a good IE etymology. The reduplication in Latin carcer could be iconic; thus, the original meaning would have been 'enclosure'. [de Vaan]
The word appears earlier in English in an obsolete medical sense of "retention of pus" (early 15c.).
incarnadine Look up incarnadine at Dictionary.com
1590s (adj.) "flesh-colored, carnation-colored, pale red, pink," from French incarnadin (16c.), from dialectal Italian incarnadino "flesh-color," from Late Latin incarnatio (see incarnation). The adjective now is archaic or obsolete. The word survives as a verb taken from the adjective, which properly would mean "to make flesh-colored," but means "make red" instead, the sense and the existence of the verb being entirely traceable to Lady Macbeth ("Macbeth" II ii.) in 1605. Its direct root might be the noun incarnadine "blood-red; flesh-color," though this is not attested until 1620s.
incarnate (adj.) Look up incarnate at Dictionary.com
late 14c., "embodied in flesh, in human or bodily form" (of souls, spirits, etc.), from Late Latin incarnatus "made flesh," a frequent word among early Christian writers, past-participle adjective from Latin incarnare "to make flesh" (see incarnation). Of qualities or abstractions, 1530s.
incarnate (v.) Look up incarnate at Dictionary.com
"clothe or embody in flesh," 1530s, a back-formation from incarnation, or else from Late Latin incarnatus "made flesh," past participle of incarnare "to make flesh; be made flesh." Meaning "make or form flesh" (as in healing a wound) is from 1670s. Related: Incarnated; incarnating.
incarnation (n.) Look up incarnation at Dictionary.com
c. 1300, "embodiment of God in the person of Christ," from Old French incarnacion "the Incarnation" (12c.), from Late Latin incarnationem (nominative incarnatio), "act of being made flesh" (used by Church writers especially in reference to God in Christ; source also of Spanish encarnacion, Italian incarnazione), noun of action from past participle stem of Late Latin incarnari "be made flesh," from in- "in" (see in- (2)) + caro (genitive carnis) "flesh" (see carnage). Glossed in Old English as inflæscnes, inlichomung. As "person or thing that is the embodiment" (of some quality, deity, etc.) from 1742.
incase (v.) Look up incase at Dictionary.com
variant of encase.
Theory of Incasement, an old theory of reproduction which assumed that when the first animal of each species was created, the germs of all other individuals of the same species which were to come from it were incased in its ova. The discovery of spermatozoa developed the theory in two opposite directions: the ovulists, or ovists, held still to the theory of incasement in the female while the animalculists, or spermists, entertained the theory of incasement in the male. [Century Dictionary]
incautious (adj.) Look up incautious at Dictionary.com
1650s, from in- (1) "not" + cautious (adj.). The Latin adjective was incautus. Related: Incautiously. Incaution (n.) is attested from 1715.
incendiarism (n.) Look up incendiarism at Dictionary.com
1670s; see incendiary + -ism. Originally figurative; the literal sense of "malicious burning" is attested from 1837.
incendiary (n.) Look up incendiary at Dictionary.com
c. 1400, "person who sets malicious fires," from Latin incendiarius "an incendiary," literally "causing a fire" (see incendiary (adj.)). Meaning "person who enflames political passions" is from 1630s.
incendiary (adj.) Look up incendiary at Dictionary.com
mid-15c., "capable of being used to set fires," from Latin incendiarius "causing a fire," from incendium "a burning, a fire, conflagration," from incendere "set on fire, light up with fire, brighten," figuratively, "incite, rouse, excite, enrage," from in- "into, in, on, upon" (see in- (2)) + candere "to shine, glow, be on fire" (see candle).

Figurative sense of "enflaming passions" is from 1610s in English. Meaning "relating to criminal burning" is from 1610s. Military use, of bombs, shells, etc., attested from 1871. The obsolete poetic verb incend is attested from c. 1500.
incense (v.2) Look up incense at Dictionary.com
"to offer incense, perfume with incense, fumigate (something) with incense," late 13c., encensen, incensen, from incense (n.) or from Old French encenser (11c.), or directly from Medieval Latin incensare.
incense (n.) Look up incense at Dictionary.com
late 13c., "gum or other substance producing a sweet smell when burned," from Old French encens (12c.), from Late Latin incensum "burnt incense," literally "that which is burnt," noun use of neuter past participle of Latin incendere "set on fire" (see incendiary). Meaning "smoke or perfume of incense" is from late 14c.
incense (v.1) Look up incense at Dictionary.com
early 15c., encensen "to arouse, inspire," from Old French incenser, from Latin incensare, frequentative of incendere "set on fire," figuratively "incite, enrage, rouse" (see incendiary). From mid-15c. as "to provoke, anger." Literal sense "to heat, make (something) hot" is from c. 1500 in English but is rare.
incensed (adj.) Look up incensed at Dictionary.com
"full of wrath, inflamed with anger," 1590s, past-participle adjective from incense (v.1). Earlier it was used in heraldry, in reference to fire-breathing animals (1570s). Distinguished in pronunciation from incensed "perfumed witrh incense" (1610s), from incense (v.2).
incent (v.) Look up incent at Dictionary.com
by 1992, U.S. government-speak, a back-formation from incentive. Related: Incented; incenting. Compare incentivize.
incentive (n.) Look up incentive at Dictionary.com
early 15c., "that which moves the mind or stirs the passion," from Late Latin incentivum, noun use of neuter of Latin adjective incentivus "setting the tune" (in Late Latin "inciting"), from past participle stem of incinere "strike up," from in- "in, into" (see in- (2)) + canere "to sing" (see chant (v.)). The sense apparently was influenced in Late Latin by association with incendere "to kindle." (Milton uses the adjective to mean "setting fire, incendiary.") Meaning "rewards meant to encourage harder work" is from 1948, short for incentive payment, etc. (see incentive (adj.)).
incentive (adj.) Look up incentive at Dictionary.com
c. 1600, "provocative, exciting, encouraging," from Late Latin incentivus "inciting" (see incentive (n.)). In reference to a system of rewards meant to encourage harder work, first attested 1943 in jargon of the U.S. war economy.
incentivize (v.) Look up incentivize at Dictionary.com
by 1970, from incentive (adj.) + -ize. Related: Incentivized; incentivizing.
incept (v.) Look up incept at Dictionary.com
1560s, "to commence, begin" (trans.), from Latin inceptus, past participle of incipere "to begin" (see inception). Related: Incepted; incepting.
inception (n.) Look up inception at Dictionary.com
early 15c., "a beginning, a starting," from Old French inception and directly from Latin inceptionem (nominative inceptio) "a beginning; an undertaking," noun of action from past participle stem of incipere "begin, take in hand," from in- "in, on" (see in- (2)) + cipere comb. form of capere "take, seize" (see capable).
inceptive (adj.) Look up inceptive at Dictionary.com
1650s, "denoting the initial point or step," from Middle French inceptif (16c.), from Latin incept-, past participle stem of incipere "to begin" (see inception). Interchangeable with inchoative. As a noun, "an inceptive verb," from 1610s.
incertitude (n.) Look up incertitude at Dictionary.com
mid-15c., "variability," from Middle French incertitude (14c.), from Late Latin incertitudinem (nominative incertitudo) "uncertainty," from in- "not, opposite of" (see in- (1)) + certitudo "that which is certain" (see certitude). From c. 1600 as "doubt, hesitation." Middle English also had incertain "uncertain" and incertainty "uncertainty," both from Old French, but both have been displaced by forms in un-.
incessancy (n.) Look up incessancy at Dictionary.com
1610s, from incessant + -cy.
incessant (adj.) Look up incessant at Dictionary.com
mid-15c., from Old French *incessant or directly from Late Latin incessantem (nominative incessans) "unceasing," from Latin in- "not" (see in- (1)) + cessans, present participle of cessare "to cease" (see cease (v.)). Related: Incessantly (early 15c.).
incest (n.) Look up incest at Dictionary.com
"the crime of sexual intercourse between near kindred," c. 1200, from Old French inceste "incest; lechery, fornication," and directly from Latin incestum "unchastity, impious unchastity," also specifically "sexual intercourse between close relatives," noun use of neuter adjective incestus "unchaste, impure," from in- "not" (see in- (1)) + castus "pure" (see caste). Old English had sibleger "incest," literally "kin-lying."
incestuous (adj.) Look up incestuous at Dictionary.com
1530s, from Late Latin incestuosus "incestuous," from Latin incestus "unchaste" (see incest). Figurative use is from 1744. Related: Incestuously; incestuousness.
inch (n.1) Look up inch at Dictionary.com
"linear measure, one-twelfth of a foot," late Old English ynce, Middle English unche (current spelling c. 1300), from Latin uncia "a twelfth part," from unus "one" (see one). An early Anglo-Saxon borrowing from Latin; not found in other Germanic languages. Transferred and figurative sense of "a very small amount, small quantity" is attested from mid-14c. As the unit of measure of rainfall from 1845. Sometimes misdivided in Middle English as a neynche. Every inch "in every respect" is from early 15c. For phrase give him an inch ... see ell.
inch (n.2) Look up inch at Dictionary.com
"small Scottish island," early 15c., from Gaelic innis (genitive innse) "island," from Celtic *inissi (cognates: Old Irish inis, Welsh ynys, Breton enez).
inch (v.) Look up inch at Dictionary.com
1590s, "move little by little" (intrans.), from inch (n.1). Meaning "drive or force by small degrees" (trans.) is from 1660s. Related: Inched; inching.
inchmeal (adv.) Look up inchmeal at Dictionary.com
"by inches, inch by inch," 1580s, from inch (n.1) + Middle English meal "fixed time, period of time, occasion" (see meal (n.1)).
inchoate (adj.) Look up inchoate at Dictionary.com
"recently or just begun," 1530s, from Latin inchoatus, past participle of inchoare, alteration of incohare "commence, begin," probably originally "to hitch up," traditionally derived from in- "in" (see in- (2)) + a verb from cohum "strap (fastened to the oxen's yoke)," a word of obscure origin. De Vaan says that as, incohere "is a frequent verb, ... its meaning can easily have derived from 'to yoke a plough to a team of oxen' ..., in other words, 'to start work.' Thus, there might be a core of truth in the ancient connection of cohum with a yoke."
inchoative (adj.) Look up inchoative at Dictionary.com
1630s, "indicating beginning or inception;" see inchoate + -ive. Especially in grammar, of verbs, "denoting the beginning of action, inceptive," 1660s.
inchworm (n.) Look up inchworm at Dictionary.com
also inch-worm, 1844, American English, from inch (v.) + worm (n.). Other old names for it included loaper caterpiller, measuring worm, and surveyor. All are from its mode of progress.
incidence (n.) Look up incidence at Dictionary.com
early 15c., "incidental matter," from Middle French incidence (15c.), from Late Latin incidentia, from incidere "to happen, befall" (see incident (n.)). Meaning "act of coming into contact with or affecting" is from 1650s. In physics, of rays of light, etc., considered with reference to direction, from 1620s.
incident (adj.) Look up incident at Dictionary.com
late 15c., "likely to happen," from Latin incidentem (nominative incidens), present participle of incidere "to happen, befall" (see incident (n.)). From 1620s as "occurring as a subordinate;" 1660s in literal sense "falling or striking upon."
incident (n.) Look up incident at Dictionary.com
early 15c., "something which occurs casually in connection with something else," from Old French incident (13c.), and directly from Latin incidentem (nominative incidens), present participle of incidere "to fall in, fall, find the way; light upon, fall in with; fall upon, occur; happen, befall," from in- "on" (see in- (2)) + -cidere, comb. form of cadere "to fall" (see case (n.1)). Broader sense of "an occurrence viewed as a separate circumstance" is from mid-15c. Euphemistic meaning "event that might trigger a crisis or political unrest" first attested 1913.
incidental (adj.) Look up incidental at Dictionary.com
"casual, occurring casually in connection with something else; of minor importance," 1640s, from Medieval Latin incidentalis, from incidens (see incident (n.)). The earlier adjective in this sense was incident (1520s). Incidentals (n.) "'occasional' expenses, etc.," is attested by 1707. Incidental music "background music" is from 1864.