em
n.(名词)The letterm. 字母m Abbr. m,MPrinting 缩写 m,M【印刷术】 The width of a square or nearly square piece of type, used as a unit of measure for matter set in that size of type.全身:一个长方形或近似方形的字形的宽度,用来度量以此宽度为单位的长度Such a measure for 2-point type; a pica.2点活字的高度;2点活字