[m] n, pl m's or ms often cap, often attrib (bef. 12c) 1 a: the 13th letter of the English alphabet b: a graphic representation of this letter c: a speech counterpart of orthographic m
2: one thousand in Roman numerals
3: a graphic device for reproducing the letter m
4: one designated m esp. as the 13th in order or class
5: something shaped like the letter M
6. a: em
2. b: pica
2.