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millimeter

(MIH-luh-MEE-ter)
A measure of length in the metric system. A millimeter is one thousandth of a meter. There are 25 millimeters in an inch.
Drawing shows different sizes of common items in millimeters (mm): a sharp pencil point (1 mm), a new crayon point (2 mm), a pencil-top eraser (5 mm), a pea (10 mm), a peanut (20 mm), and a lime (50 mm). Also shown is a 2-centimeter (cm) ruler that shows 10 mm is equal to 1 cm.Enlarge this image in new window
Tumor sizes are often measured in millimeters (mm) or centimeters. Common items that can be used to show tumor size in mm include: a sharp pencil point (1 mm), a new crayon point (2 mm), a pencil-top eraser (5 mm), a pea (10 mm), a peanut (20 mm), and a lime (50 mm).
Search NCI's Dictionary of Cancer Terms