em

em  (m)

n.

1. The letter m.

2. Printing

a. 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.

b. Such a measure for 12-point type; a pica.

Thesaurus

Noun	1.	em - a quad with a square body; "since `em quad' is hard to distinguish from `en quad', printers sometimes called it a `mutton quad'" em quad, mutton quad area unit, square measure - a system of units used to measure areas
	2.	em - a linear unit (1/6 inch) used in printing pica em, pica linear measure, linear unit - a unit of measurement of length in, inch - a unit of length equal to one twelfth of a foot point - a linear unit used to measure the size of type; approximately 1/72 inch en, nut - half the width of an em