Nouns

(n)iodine, iodin, I, atomic number 53a nonmetallic element belonging to the halogens; used especially in medicine and photography and in dyes; occurs naturally only in combination in small quantities (as in sea water or rocks)
(n)one, 1, I, ace, single, unitythe smallest whole number or a numeral representing this number“he has the one but will need a two and three to go with it”, “they had lunch at one”
(n)I, ithe 9th letter of the Roman alphabet