any of the symbols used in a system (numeral system) of numerical notation based on the ancient Roman system. The symbols are I, V, X, L, C, D, and M, standing, respectively, for 1, 5, 10, 50, 100, 500, and 1,000 in the Hindu-Arabic numeral system. A symbol placed after another of equal or greater value adds its value—e.g., II = 2 and LX = 60. A symbol placed before one of greater value subtracts its value—e.g., IV = 4, XL = 40, and CD = 400.