u

I. noun (plural u's or us) Usage: often capitalized, often attributive Date: before 12th century 1. a. the 21st letter of the English alphabet b. a graphic representation of this letter c. a speech counterpart of orthographic u 2. a graphic device for reproducing the letter u 3. one designated u especially as the 21st in order or class 4. [abbreviation for unsatisfactory] a. a grade rating a student's work as unsatisfactory b. one graded or rated with a U 5. something shaped like the letter U II. abbreviation 1. unit 2. unsymmetrical 3. upper