The Collaborative International Dictionary of English v.0.48:

mm \mm\, n.
   millimeter; -- the IS standard abbreviation. [abbreviation]
   [PJC]

The Collaborative International Dictionary of English v.0.48:

mM \mM\, a. Chem.)
   millimolar; -- the IS standard abbreviation. [abbreviation]
   [PJC]

The Collaborative International Dictionary of English v.0.48:

Monsieur \Mon*sieur"\, n.; pl. Messieurs. [F., fr. mon my +
   Sieur, abbrev. of seigneur lord. See Monseigneur.]
   1. The common title of civility in France in speaking to, or
      of, a man; Mr. or Sir. [Represented by the abbreviation M.
      or Mons. in the singular, and by MM. or Messrs. in the
      plural.]
      [1913 Webster]

   2. The oldest brother of the king of France.
      [1913 Webster]

   3. A Frenchman. [Contemptuous] --Shak.
      [1913 Webster]

V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

MM
       Media Manager (Novell, Netware, SMS)


V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

MM
       Military Message (mil.)


V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

MM
       Mobile Management (RR, CM, GSM, mobile-systems)