m
     adj : denoting a quantity consisting of 1,000 items or units [syn:
            {thousand}, {a thousand}, {one thousand}, {1000}, {k}]
     n 1: the basic unit of length adopted under the Systeme
          International d'Unites (approximately 1.094 yards) [syn:
           {meter}, {metre}]
     2: concentration measured by the number of moles of solute per
        liter of solvent [syn: {molarity}, {molar concentration}]
     3: the cardinal number that is the product of 10 and 100 [syn:
        {thousand}, {one thousand}, {1000}, {K}, {chiliad}, {G}, {grand},
         {thou}, {yard}]
     4: the 13th letter of the Roman alphabet
Source: WordNet® 2.0

M pref. (on units) suff. (on numbers) [SI] See {{quantifiers}}.


Source: The Jargon File

M$ Common net abbreviation for Microsoft, everybody's least favorite
   monopoly.


Source: The Jargon File