m

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

• noun The 13th letter of the modern English alphabet.
• noun Any of the speech sounds represented by the letter m.
• noun The 13th in a series.
• noun Something shaped like the letter M.
• abbreviation Grammar masculine
• abbreviation Physics mass
• abbreviation meter (measurement)
• abbreviation mile
• abbreviation minute
• abbreviation Physics modulus
• abbreviation Chemistry molality

from The Century Dictionary.

• noun An abbreviation of the Latin Medicinæ Doctor, Doctor of Medicine (see doctor, 2); in musical notation, of mano destra (Italian) or main droite (French), ‘right hand,’ indicating a passage to be performed by the right hand.
• noun An abbreviation of Middle Dutch;
• noun of months (after) date.
• noun An abbreviation
• noun of Latin Musicæ Graduatus. Graduate of Music.
• An abbreviation
• of Master of Laws;
• of Master of Literature;
• of muzzle-loading.
• noun An abbreviation of Master of Science;
• noun of Master of Surgery;
• noun of month's sight;
• noun of Latin Memoriæ Sacrum, sacred to the memory (of, etc.).
• An abbreviation of Methodist Episcopal; of Mining Engineer: as, John Smith, M. E.; of Middle English: used (as Middle English) in the etymologies of this work.
• noun An abbreviation of Maelzel's metronome. See metronome.
• noun An abbreviation of the Latin Medicinæ Baccalaureus, Bachelor of Medicine;
• noun of the Latin Musicæ Baccalaureus, Bachelor of Music;
• noun of “mark of the beast,” in allusion to the popular belief that the garment described below smacked of popery.
• As a symbol:
• M denotes magnetic moment: usually printed in old English; a gaseous pressure of the millionth of an atmosphere.
• μ denotes magnetic permeability or the specific conductivity of any substance for lines of magnetic force; the coefficient of friction.
• m stands for the intensity or strength of a magnetic pole.
• m stands for square meters, m for cubic meters.
• As an abbreviation:
• In titles, M. stands also for Marquis, Matthew (a book of the New Testament), and Monsieur.
• In a ship's log-book, masculine is an abbreviation of moderate.
• In a chart, masculine stands for mud; in meteorology, for mist; in ophthalmol., for myopia.
• In pharmacy, M. or masculine stands for macerare (macerate), manipulus (a handful), mensura (measure or by measure), minimum (minim), misce (mix), mistura (mixture).
• In astronomical tables, M. or masculine (abbreviation of L. meridies) indicates meridian or meridional: 12 M. stands for noon. See A. M. and P. M.
• In astronomy, M. stands for Messier, referring to his catalogue of 103 nebulæ and star-clusters: thus, 51M. or M.51 is the famous whirlpool nebula.
• M. stands for Monday; M. or masculine, for mile or miles, mill or mills, month or months, moon, muster; m., for married, masculine, middle, minutes, morning, and the Latin mille (a thousand).
• noun An abbreviation of Master of the Rolls.
• noun An abbreviation of mean time.
• noun See A. M. .
• noun An abbreviation of Member of Congress.
• An abbreviation of Major-General.
• In musical notation, an abbreviation of the French main gauche (left hand), indicating that a note or passage is to be played with the left hand.
• noun An abbreviation of Member of Parliament.
• noun An abbreviation of the Latin Magister Chirurgiæ, Master of Surgery;