M: Letterform and Roman Numeral

This atlas covers the Latin M's phonetic descent from Phoenician mem through Greek mu elsewhere. Graphically, mem's wavy water-sign straightened over the alphabet's Greek and Etruscan transmission into a letter built from vertical strokes; the number of strokes forming its middle section varied between three and four in different ancient scripts before Roman usage settled on the familiar four-stroke, W-topped capital M used today, with the lowercase m simply a smaller, rounder version of the same structure fixed by medieval cursive hands. Separately, M is one of seven Latin letters also used as a Roman numeral, standing for one thousand, the largest of the standard set.

M's numeral value is often explained as reinforced, if not directly caused, by its being the first letter of the Latin word mille, thousand, though scholars of the numeral system note this may be a later folk association layered onto a symbol whose graphic origin, like several of the larger Roman numerals, is not fully settled; some accounts derive the numeral shape from an earlier non-alphabetic mark only later assimilated to the letter M. As with the other numeral letters, this value is a separate notational system from the alphabet's phonetic and mystical traditions and carries no comparable esoteric weight of its own.