A measure of length in the metric system. A millimeter is one thousandth of a meter. There are 25 millimeters in an inch.
Source: NCI Dictionary of Cancer Terms
Caption: Millimeters (mm). A sharp pencil point is about 1 mm, a new crayon point is about 2 mm, and a new pencil eraser is about 5 mm.Date last modified: 2008-10-17