i

I. noun (plural i's or is) Usage: often capitalized, often attributive Date: before 12th century 1. a. the 9th letter of the English alphabet b. a graphic representation of this letter c. a speech counterpart of orthographic i 2. one — see number table 3. a graphic device for reproducing the letter i 4. one designated i especially as the ninth in order or class 5. something shaped like the letter I 6. a unit vector parallel to the x-axis 7. [abbreviation for incomplete] a. a grade rating a student's work as incomplete b. one graded or rated with an I 8. I formation II. abbreviation 1. industrial 2. initial 3. intelligence 4. intensity 5. intransitive 6. island; isle III. symbol imaginary unit