Etymology — The origins of English words

* jack + light. Probably from jack (“a male servant of any rank”), later associated with a boy servant or any boy, and later still with a knave: a rogue, thief, or deceitful man. * Possibly also related to Spanish jaque (“a bully”).

From Latin Iovis (“Jove, Jupiter”) + -an, analysable as Jove + -ian. Piecewise doublet of Zeusian.

From Late Latin intramuscularis, from prefix intra-, "within", + musculum, "muscle".

From past participle of inwork.

First attested in c. 1577; borrowed from Latin iūdicātus, perfect passive participle of iūdicō (see -ate (verb-forming suffix)) and possibly partly a clipping of adjudicate. Doublet of judge.

From French irréligion, from Latin irreligiō. By surface analysis, ir- + religion.

Name of a fourth-century saint. The feminine equivalent of Isidore, from Ancient Greek Ἰσιδώρα (Isidṓra, “gift of Isis”).

From French inexact.

From Middle French inextricable, from Latin inextricabilis.

Learned borrowing from Late Latin irrefrāgābilis (“irrefragable”) + English -able (suffix forming adjectives with the sense ‘able or fit to be done’). Irrefrāgābilis is derived from Latin ir- (variant of in- (prefix meaning ‘not’)) + refrāgārī + -bilis (suffix forming adjectives indicating a capacity or worth of being acted upon); while refrāgārī is the present active infinitive of refrāgor (“to oppose, resist; to gainsay, thwart”) (further etymology uncertain, possibly from re- (prefix meaning ‘again’) + fragor (“a breaking, shattering; a crash; din, uproar”) (from frangō (“to break, shatter”), ultimately from Proto-Indo-European *bʰreg- (“to break”))), formed as an antonym of suffrāgōr, the first-person singular present passive indicative of suffrāgō (“to support; to vote for”).

From ironic + -al. Attested since the 1570s.

The adjective is derived from French incarnadin, incarnadine, from Italian incarnadino, a variant of incarnatino (“carnation; flesh colour”), from incarnato (“embodied, incarnate”) + -ino (suffix forming adjectives denoting composition, colour, or other qualities). Incarnato is derived from Ecclesiastical Latin and Late Latin incarnātus (“having been made incarnate”), the perfect passive participle of incarnō (“to become or make incarnate; to make into flesh”), from in- (suffix meaning ‘in, inside, within’) + Latin carō (“flesh, meat; body”) (ultimately from Proto-Indo-European *(s)ker- (“to cut off”)) + -ō (suffix forming regular first-conjugation verbs). By surface analysis, in- + Latin carn- + -ade + -ine. The noun and verb are derived from the adjective. Adjective senses 2 and 3 (“of the blood-red colour of raw flesh; (figurative) bloostained, bloody”) and noun sense 2 (“blood-red colour of raw flesh”) are due to William Shakespeare’s use of the word as a verb in Macbeth (c. 1606): see the quotation below.

From Middle French incertitude.

Borrowed from French ingénue, the feminine form of ingénu (“guileless”), originally from the Latin ingenuus (“ingenuous”).

Via Russian кафта́н (kaftán), from Ottoman Turkish قفتان (kaftan), from Classical Persian خَفْتَان (xaftān), which occurs already in the Shahnameh.

Probably by way of French intercedent (adjective), which seems to be more commonly attested than this English adjective. Ultimately from Latin intercedens, present participle of intercedere, and possibly borrowed twice by English, with the later borrowing being a learned borrowing.

From Ancient Greek κάκιστος (kákistos, “worst”), superlative of κακός (kakós, “bad”) + -κρατία (-kratía, “power, rule, government”) (corresponding to -cracy). The word was used, perhaps re-coined, by the English author Thomas Love Peacock (1785–1866) in his 1829 novella The Misfortunes of Elphin as the opposite of aristocracy (see second quotation).

Coined around 1800, from Latin iris, iridis (“rainbow”) + -escent.

From in- + submissive.

Borrowed from French djebel, from Arabic جَبَل (jabal, “mountain”).

From inaccurate + -ly or in- + accurately.

From Latin ioculātrīx. By surface analysis, joculator + -trix.

From in- + constructible.

From Late Middle English insaciate, insaciat, insacyate (“insatiable”), from Latin insatiātus, from in- (prefix meaning ‘not’) + satiātus (“satisfied; having been satisfied”) (perfect passive participle of satiō (“to satisfy”), from satis (“enough; filled; plenty”) (ultimately from Proto-Indo-European *seh₂- (“to satiate, satisfy”)) + -ō (suffix forming regular first-conjugation verbs)).