I (i).
1. I, the ninth letter of the English alphabet, takes its form from the Phœnician, through the Latin and the Greek. The Phœnician letter was probably of Egyptian origin. Its original value was nearly the same as that of the Italian I, or long e as in mete. Etymologically I is most closely related to e, y, j, g; as in d int, d ent, b everage, L. b ibere; E. k in, AS. c ynn; E. th in, AS. þ ynne; E. domin ion, don jon, dun geon. In English I has two principal vowel sounds: the long sound, as in pine, ice; and the short sound, as in pin. It has also three other sounds: ( a) That of e in term, as in thirst. ( b) That of e in mete (in words of foreign origin), as in machine, pique, regime. ( c) That of consonant y (in many words in which it precedes another vowel), as in bunion, million, filial, Christian, etc. It enters into several digraphs, as in fail, field, seize, feign. friend; and with o often forms a proper diphtong, as in oil, join, coin. See Guide to Pronunciation, §§ 98-106. The dot which we place over the small or lower case i dates only from the 14th century. The sounds of I and J were originally represented by the same character, and even after the introduction of the form J into English dictionaries, words containing these letters were, till a comparatively recent time, classed together.
2. In our old authors, I was often used for a. (or aye), yes, which is pronounced nearly like it.
3. As a numeral, I stands for 1, II for 2, etc.

I (i), pron. [ poss. My (mi) or Mine (min); object. Me (me). pl. nom. We (we); poss. Our (our) or Ours (ourz); object. Us (us).] [OE. i, ich, ic, AS. ic; akin to OS. & D. ik, OHG. ih, G. ich, Icel. ek, Dan. jeg, Sw. jag, Goth. ik, OSlav. az’, Russ. ia, W. i, L. ego, Gr. ’egw•, ’egw•n, Skr. aham. rad.179. Cf. Egoism.] The nominative case of the pronoun of the first person; the word with which a speaker or writer denotes himself.

Iamatology
I•am•a•tol´o•gy, n. [Gr.,, medicine + -logy.] (Med.) Materia Medica; that branch of therapeutics which treats of remedies.

Iambic
I•am´bic, a. [L. iambicus, Gr. : cf. F. iambique.]
1. (Pros.) Consisting of a short syllable followed by a long one, or of an unaccented syllable followed by an accented; as an iambic foot.
2. Pertaining to, or composed of, iambics; as an iambic verse; iambic meter. See Lambus.

Iambic
I•am´bic, n.
1. (Pros.) (a) An iambic foot; an iambus. (b) A verse composed of iambic feet. The following couplet consists of iambic verses.
"Thy gen- | ius calls | thee not | to pur- | chase fame In keen | iam- | bics, but | mild an- | agram." Dryden.
2. A satirical poem (such poems having been anciently written in iambic verse); a satire; a lampoon.

Ianthina
I•an´thi•na, n. ; pl. L. Ianthinae (#), E. Ianthinas (#). [NL., fr. L. ianthinus violet-blue, Gr. ; violet + flower.] (Zoöl.) Any gastropod of the genus Ianthina, of which various species are found living in mid ocean; — called also purple shell, and violet snail. [Written also janthina.] It floats at the surface by means of a raft, which it constructs by forming and uniting together air bubbles of hardened mucus. The Tyrian purple of the ancients was obtained in part from mollusks of this genus.