What is mm meaning?

"mm" is an abbreviation for millimeter, which is a unit of measurement used to describe length or distance. One millimeter is equivalent to one-thousandth of a meter or 0.03937 inches. The abbreviation "mm" is often used in engineering, manufacturing, and construction industries to specify the dimensions of objects or materials. It may also be used in medical fields to describe the size of tumors or other abnormalities on a patient's body.