King James Dictionary 
I is the ninth letter,and the third vowel of the English Alphabet. We receive it through the Latin and Greek from the Shemitic jod,je, or ye, in Greek iwra,whence our English word jot. The vowel in French, and in most European languages, has the long fine sound which we express by e in me, or ee in seen, meek. This sound we retain in some foreign words which are naturalized in our language, as in machine, intrigue. But in most English words this long sound is shortened, as in holiness, pity, gift in which words the sound of 1coincides with that of y in hypocrite,cycle,and at the end of words, in unaccented syllables, as in holy, glory. It is this short sound of the French and Italian 1which we hear in the pronunciation of been, which we pronounce bin. After 50this letter has sometimes the liquid sound of y, as in million, pronounced milyon. This sound corresponds with that of the Hebrews, as in Joseph, which in Syria is pronounced Yoseph,and with the sound of the German j, as in ja, jahr, that is ya, yahr.
The sound of 1long, as in fine, kind, arise, is diphthongal it begins with a sound approaching that of broad a, but it is not exactly the same, as the organs are not opened to the same extent, and therefore the sound begins a little above that of aw. The sound, if continued,closes with one that nearly approaches to that of e long. This sound can be learned only by the ear. This letter enters into several digraphs, as in fail, field,seize, feign, vein, friend and with o in oil,join, coin,it helps to form a proper diphthong.
No English word ends with 1but when the sound of the letter occurs at the end of a word,it is expressed by y.
As a numeral I signifies one, and stands for as many units as it is repeated in times, as II, two, III, three, &c. When it stands before V or X, it subtracts itself,and the numerals denote one less than the V or the X. Thus IV expresses four, one less than V, five IX stands for nine, one less than X, ten. But when it is placed after V or X, it denotes the addition of an unit, or as many units as the letter is repeated in times. Thus VI is five and one, or six, and XI is ten and one, or eleven VIII stands for five and three, or eight, &c.
I, formerly prefixed to some English words, as in ibuilt, is a contraction of the Saxon prefix ge and more generally this was written y.
I, pron. L. ego. The pronoun of the first person the word which expresses one's self, or that by which a speaker or writer denotes himself. It is only the nominative case of the pronoun in the other cases we use me. I am attached to study study delights me. We often hear in popular language the phrase it is me, which is now considered to be ungrammatical, for it is I. But the phrase may have come down to us from the use of the Welsh mi, or from the French use of the phrase, moi.
In the plural, we use we, and us, which appear to be words radically distinct from I.
Johnson observes that Shakespeare uses I for ay or yes. In this he is not followed, and the use is incorrect.
Vine's Expository Dictionary of NT Words 
is the nominative case of the first personal pronoun. The pronoun, "I," however, generally forms a part of the verb itself in Greek; thus luo itself means "I loose," the pronoun being incorporated in the verb form. Where the pronoun ego is added to the verb, it is almost invariably, if not entirely, emphatic. The emphasis may not be so apparent in some instances, as e.g., Matthew 10:16 , but even here it may be taken that something more of stress is present than if the pronoun were omitted. By far the greater number of instances are found in the Gospel of John, and there in the utterances of the Lord concerning Himself, e.g., John 4:14,26,32,38; 5:34,36,43,45; 6:35,40,41,48,51 (twice),63,70; instances in the Epistles are Romans 7:9,14,17,20 (twice), 24,25; there are more in that chapter than in any other outside the Gospel of John. In other cases of the pronoun than the nominative, the pronoun is usually more necessary to the meaning, apart from any stress. For k'ago (i.e., kai ego), see Even , Note (6).
Webster's Dictionary 
(prefix.) See Y-.