mm

from The American Heritage® Dictionary of the English Language, 5th Edition.

• abbreviation millimeter

from The Century Dictionary.

• noun An abbreviation of millimeter.
• An abbreviation
• of the plural of Latin words commonly abbreviated masculine, as magistri;
• of the Latin matrimonium;
• of the Latin meritissimus.
• noun An abbreviation (in French) of Messieurs (gentlemen, sirs).
• An abbreviation
• of their Majesties;
• of Martyrs.
• An abbreviation of magnetomotive force.
• An abbreviation of square millimeter.
• An abbreviation of Master of Mechanical Engineering.
• An abbreviation of cubic millimeter. μμ. A symbol used to denote a thousandth of a micron or a millionth of a millimeter.

from the GNU version of the Collaborative International Dictionary of English.

• adjective Chem.), abbreviation millimolar; -- the IS standard abbreviation.
• noun abbreviation millimeter; -- the IS standard abbreviation.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun metrology Symbol for the millimeter (millimetre), an SI unit of length equal to 10−3 meters (metres).
• noun A Roman numeral representing two thousand (2000).
• abbreviation month in two-digit numeric format, as in: dd/mm/yyyy
• interjection Alternative form of mmm.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a metric unit of length equal to one thousandth of a meter
• noun the pace of music measured by the number of beats occurring in 60 seconds