What's the difference between i.e. and e.g.?
Old English me (dative), me, mec (accusative); oblique cases of I, from Proto-Germanic *meke (accusative), *mes (dative), cf. Old Frisian mi/mir, Old Saxon mi, Middle Dutch mi, Dutch mij, Old High German mih/mir, German mich/mir, Old Norse mik/mer, Gothic mik/mis; from PIE root *me-, oblique form of the personal pronoun of the first person singular (nominative *eg; see I); cf. Sanskrit, Avestan mam, Greek eme, Latin me, mihi, Old Irish me, Welsh mi "me," Old Church Slavonic me, Hittite ammuk.
Erroneous or vulgar use for nominative (e.g. it is me) attested from c.1500. Dative preserved in obsolete meseems, methinks and expressions such as sing me a song ("dative of interest"). Reflexively, "myself, for myself, to myself" from late Old English.
12c. shortening of Old English ic, first person singular nominative pronoun, from Proto-Germanic *ekan (cf. Old Frisian ik, Old Norse ek, Norwegian eg, Danish jeg, Old High German ih, German ich, Gothic ik), from PIE *eg-, nominative form of the first person singular pronoun (cf. Sanskrit aham, Hittite uk, Latin ego (source of French Je), Greek ego, Russian ja, Lithuanian aš). Reduced to i by mid-12c. in northern England, it began to be capitalized mid-13c. to mark it as a distinct word and avoid misreading in handwritten manuscripts.
The reason for writing I is ... the orthographic habit in the middle ages of using a 'long i' (that is, j or I) whenever the letter was isolated or formed the last letter of a group; the numeral 'one' was written j or I (and three iij, etc.), just as much as the pronoun. [Otto Jespersen, "Growth and Structure of the English Language," p.233]The form ich or ik, especially before vowels, lingered in northern England until c.1400 and survived in southern dialects until 18c. The dot on the "small" letter -i- began to appear in 11c. Latin manuscripts, to distinguish the letter from the stroke of another letter (such as -m- or -n-). Originally a diacritic, it was reduced to a dot with the introduction of Roman type fonts.
abbreviation of Middle English, attested by 1874.
The symbol for the element iodine.
iThe symbol for current.
The number whose square is equal to -1. Numbers expressed in terms of i are called imaginary or complex numbers.