- M1(also m)noun (plural Ms or M's)1》 the thirteenth letter of the alphabet.2》 denoting the next after L in a set of items, categories, etc.3》 the Roman numeral for 1,000. [from L. mille.]————————M2abbreviation1》 Cricket (on scorecards) maiden over(s).2》 male.3》 Malta (international vehicle registration).4》 medium (as a clothes size).5》 mega-.6》 Astronomy Messier (catalogue of nebulae).7》 Chemistry (with reference to solutions) molar.8》 used with following numeral in measures of money supply.9》 Monsieur.10》 (in UK road designations) motorway.symbol Physics mutual inductance.
English new terms dictionary. 2014.