Definition of: m, M

(em) noun plural m's, M's or ms, Ms or ems (emz)
1. The 13th letter of the English alphabet: from Phoenician mem, Greek mu, Roman M.
2. The sound of the letter m, usually a voiced, bilabial nasal. See ALPHABET.
—symbol
1. The Roman numeral 1,000. See under NUMERAL.
2. Printing An em.