the GNU version of the Collaborative International Dictionary of English
n. A lineal measure in the metric system, containing the thousandth part of a meter; equal to .03937 of an inch. See 3d meter.
The Century Dictionary and Cyclopedia
n. The thousandth part of a meter, equal to 0.03937 inch, or nearly inch. It is denoted by mm.: as, 25.4 mm. is 1 inch.
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
n. a metric unit of length equal to one thousandth of a meter
Word Usage
"The most recent technology that's out there today, which is in several airports throughout the United States in a voluntary basis, uses what we call a millimeter wave system, which actually looks under the clothing of an individual."