- I[I 词源字典]
- I: [OE] Essentially all the Indo-European languages share the same first person singular pronoun, although naturally it has diverged in form over the millennia. French has je, for example, Italian io, Russian ja, and Greek egó. The prehistoric Germanic pronoun was *eka, and this has produced German ich, Dutch ik, Swedish jag, Danish jeg, and English I. The affirmative answer aye ‘yes’  is probably ultimately the same word as I.
=> aye, ego[I etymology, I origin, 英语词源]
- ibex: see ivy
- ice: [OE] Ice is a widespread word among the Germanic languages – German has eis, for instance. Dutch ijs, and Swedish and Danish is – but beyond that its connections are somewhat dubious. Some of the more easterly Indo- European languages have or had similar-looking forms, including Old Iranian isu- ‘frosty, icy’, modern Iranian yak ‘ice’, and Afghan asaī ‘frost’, which suggest the possibility of a common source. Iceberg  was perhaps an adaptation of Danish and Norwegian isberg, literally ‘ice mountain’.
- ichneumon:  Ichneumon comes from a Greek word which meant literally ‘tracker’. This was ikhneúmōn, a derivative of íkhnos ‘track, footstep’. Aristotle used it as the name for a species of wasp that hunted spiders, and it was adopted into English in this sense for the ichneumon fly, a wasplike insect with parasitic larvae, in the 17th century. Its original English application, however, was to a variety of African mongoose which ‘tracks down’ or hunts out crocodile eggs.
- ichthyology: see fish
- icicle:  Historically, icicle is a tautology, meaning literally ‘ice icicle’. It originated in Middle English as a compound of ice and ickel ‘icicle’. This word, which survived dialectally into the 20th century as ickle, goes back to Old English gicel, which in turn was descended from a prehistoric Germanic *jakulaz (source also of modern Icelandic jökull ‘glacier’).
- icon:  The etymological idea underlying icon is of ‘similarity’. It comes via Latin īcōn from Greek eikón, which was derived from a prehistoric base meaning ‘be like’. From ‘likeness, similarity’, eikón progressed semantically via ‘image’ to ‘portrait, picture’. That was the general sense in which English acquired the word (‘The Icon, or forme of the same birde, I have caused thus to bee figured’, John Bossewell, Workes of Armorie 1572), and it was not until the early 19th century that the particular application to a ‘sacred portrait in the Eastern Orthodox church’ entered the language.
- iconoclast:  The original iconoclasts were members of the Eastern Orthodox church in the 8th and 9th centuries AD who were opposed to the use or worship of religious images. In more extreme cases their opposition took the form of smashing icons (the word iconoclast comes via medieval Latin from medieval Greek eikonoklástēs, a compound formed from eikón ‘icon’ and the verb klan ‘break’).
The term subsequently came to be applied to extreme Protestants in England in the 16th and 17th centuries who expressed their disapproval of graven images (and popish practices in general) in similar ways. Its general use for an ‘attacker of orthodoxy’ dates from the early 19th century.
- idea:  Etymologically, an idea is the ‘look’ of something – it comes ultimately from the same source as produced the Greek verb ídein ‘see’. Greek idéā itself was used by Plato in the specialized sense ‘archetypal form of something’, which survives in the derived adjective ideal , but as far as the modern English noun is concerned, its sense ‘notion, mental conception’ developed (in Greek) via ‘look, appearance’, ‘image’, and ‘mental image’. Ideology  is a derivative, coined originally in French at the end of the 18th century.
=> ideology, idol
- identity:  The historical meaning of identity is best preserved in its derivative identical  – ‘the same’. For its ultimate source was Latin idem ‘same’, a pronoun (formed from id ‘it, that one’ with the suffix -dem) used in English since the 17th century for referring to a previously cited author or text. This formed the basis of late Latin identitās, which meant literally ‘sameness’; the main meaning of its English descendant identity, ‘individuality, set of definitive characteristics’, arose from the notion of something always being the same or always being itself (rather than something else).
- ideology: see idea
- idiosyncracy:  Greek idios meant ‘of a particular person, personal, private, own’. Among the words it has contributed to English are idiom  (etymologically ‘one’s own particular way of speaking’), idiot, and idiosyncracy. This was a compound formed in Greek with súgkrāsis, itself a compound noun made up of sún ‘together’ and krāsis ‘mixture’ (a relative of English crater). Súgkrāsis originally meant literally ‘mixture’, but it was later used metaphorically for ‘mixture of personal characteristics, temperament’, and so idiosúgkrāsis was ‘one’s own particular mix of traits’.
=> idiom, idiot
- idiot:  The etymological idea underlying idiot is of a ‘private individual’. That is what Greek idiótēs (a derivative of ídios ‘personal, private’) originally meant. It was extended to the ordinary ‘common man’, particularly a lay person without any specialized knowledge, and so came to be used rather patronizingly for an ‘ignorant person’. It is this derogatory sense that has come down to English via Latin idiōta and Old French idiot.
- idle: [OE] ‘Lazy’ is only a secondary meaning of idle. It originally meant ‘useless, worthless’ (as in ‘idle threats’), and the sense ‘lazy’ did not develop until the 13th century (the Old English words for ‘lazy’ were slow and slack). Idle is shared by other West Germanic languages, and its relatives (German eitel ‘vain, futile’ and Dutch ijdel ‘vain, useless, conceited’) point up its original English meaning, but it is not known what its ultimate origins are.
- idol:  Greek eidos meant ‘form, shape’ (it came from the same root as idéā, source of English idea). From it was derived eídōlon, which originally meant ‘appearance’, and in particular ‘apparition, phantom’. It developed from there to ‘image’, either a ‘mental image’ or a ‘physical image’, such as a ‘statue’; and in the early Christian era it and its Latin descendant īdōlum were used for an ‘image of a false god’.
English acquired the word via Old French idole or idele. Another English offspring of Greek eidos, in the sense ‘picture’, is idyll , which was borrowed from the diminutive form eidúllion ‘little picture’, hence ‘small descriptive poem’.
=> idea, idyll
- if: [OE] The Old English version of if was gif, but its initial g was closer to modern English y in pronunciation than to g, and the conjunction gradually evolved through Middle English yif to if. It is not known where it ultimately came from; it is evidently connected with Old High German iba ‘condition’ and Old Norse ef ‘doubt’, but whether it started life as a noun like these or was from the beginning a conjunction is not clear. Its surviving Germanic relatives are German ob ‘whether’ and Dutch of ‘if’.
- ignite:  The Latin word for ‘fire’ was ignis (it has been traced back to a prehistoric Indo- European *egni- or *ogni-, which also produced Sanskrit agni- and Lithuanian ugnìs ‘fire’). From it were derived the verb ignīre ‘set light to’, source of English ignite, and the adjective igneus, from which English got igneous . Another contribution the Latin noun has made to English is ignis fatuus ‘will-o’-the-wisp’ , literally ‘foolish fire’, so called perhaps from its erratic flickering, as if scatter-brained.
- ignoble: see noble
- ignore:  The Latin verb for ‘not know’, and hence ‘disregard’, was īgnōrāre, which was formed with a negative prefix from the stem gnō- ‘know’ (ultimate source also of English narrate). From it English got ignore, and from its derivative īgnōrantia the noun ignorance . Its first person present plural was īgnōrāmus ‘we do not know’. This was originally used in English in the 16th century as a legal term, in the sense ‘we ignore’, used by a Grand Jury in rejecting an indictment for lack of evidence. Not until the early 17th century was it applied to an ‘ignorant person’.
- iliac: see jade