M

1. M, the thirteenth letter of the English alphabet, is a vocal consonant, and from the manner of its formation, is called the labio-nasal consonant. See Guide to Pronunciation, // 178-180, 242.
2. As a numeral, stands for one thousand, both in English and Latin.
3. (n.) A quadrat, the face or top of which is a perfect square; also, the size of such a square in any given size of type, used as the unit of measurement for that type: 500 m's of pica would be a piece of matter whose length and breadth in pica m's multiplied together produce that number.
4. (n.) A brand or stigma, having the shape of an M, formerly impressed on one convicted of manslaughter and admitted to the benefit of clergy.