A traditional unit of area used in printing and advertising, equal to 1/14 inch (1.814 millimeters) multiplied by the width of the printed line. This usage is short for agate line
Russ Rowlett (Director), How Many? A Dictionary of Units of Measurement, Center for Mathematics and Science Education University of North Carolina, USA 2005. http://www.unc.edu/~rowlett/units/dictA.html, (Unit of Meas and Covr Factors - Amer) {608}