The thirteenth letter and tenth consonant in the English alphabet.As a numeral, in the Roman system, M denotes 1,000. With a dash or stroke over it (M), it stands for a thousand times a thousand, or 1,000,000.As a symbolIn the mnemonic words of logic (see mood), m indicates a transposition (metathesis) of the premises in the reduction.Formerly, M was a brand impressed on one convicted of manslaughter and admitted to the benefit of clergy.As an abbreviationIn titles, M. stands for Magister or Master, as in A. M.; for Medicinæ or Medicine, as in M. D.; or for Member, as in M. C, member of Congress, and M. P., member of Parliament.In mech., m. stands for mass.In dental formulæ, in zoöl., m. stands for molar, and dm. for deciduous molar.In mathematics, M or μ stands for modulus; in higher geom., m or μ for the degree of a curve.In astronomy and metrology, m. stands for minute (of time), and for meter; mm. for millimeter; and μ for micron or micromillimeter.In musical notation, M. stands for mano (main), mezzo, metronome, and in organ-music for manual. See M. D., M. M., M. S.In a ship's log-book, masculine is an abbreviation of mist.In printing, the square or quadrate of any body of type: more commonly spelled out, em (which see).n. See A. M. .n. An abbreviation of Member of Congress.n. 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.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.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.n. An abbreviation of Middle Latin or Medieval Latin.n. An abbreviation of Maelzel's metronome. See metronome.n. An abbreviation of Member of Parliament.n. In music, an abbreviation of mano sinistra, ‘the left hand,’ noting a note or passage to be played with the left hand.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).n. An abbreviation of the Latin Medicinæ Baccalaureus, Bachelor of Medicine;n. of the Latin Musicæ Baccalaureus, Bachelor of Music;n. of “mark of the beast,” in allusion to the popular belief that the garment described below smacked of popery.n. An abbreviation of the Latin Magister Chirurgiæ, Master of Surgery;n. of Master of Ceremonies.n. An abbreviation of Middle Dutch;n. of months (after) date.n. An abbreviation of Master of Engineering;n. of Mechanical Engineer;n. of Military Engineer;n. of Most Excellent.n. An abbreviationn. of Latin Musicæ Graduatus. Graduate of Music.n. Abbreviations of Mœsogothic.n. An abbreviationn. of Master of Horticulture;n. of Most Honorable.An abbreviationof Master of Laws;of Master of Literature;of muzzle-loading.n. An abbreviation of Master of Oratory.n. An abbreviationn. of Master of Painting;n. of man-power;n. of Member of Police;n. of Methodist Protestant;n. of Metropolitan Police;n. of the Latin millia passuum, a thousand paces: the Roman mile;n. of Municipal Police.n. An abbreviation of Master of the Rolls.n. An abbreviation of Master of Science;n. of Master of Surgery;n. of month's sight;n. of Latin Memoriæ Sacrum, sacred to the memory (of, etc.).n. An abbreviation of mean time.n. An abbreviationn. of the Latin Medicus Veterinarius, veterinary physician;n. in music, of the Italian mezza voce, with half the force of the voice;n. in experimental psychology, of mean variation.n. An abbreviationn. of Most Worshipful;n. of Most Worthy.