m

UK: 'M', 'm': /ˈɛm/ US: 'M', 'm': /ɛm/ ,'M', 'm': (em)

Collins Concise English Dictionary © HarperCollins Publishers::

m, M / ɛm/ noun (m's, M's, Ms)

1. the 13th letter and tenth consonant of the modern English alphabet
2. a speech sound represented by this letter, usually a bilabial nasal, as in mat

m symbol

1. metre(s)
2. mile(s)
3. milli-
4. minute(s)

WordReference Random House Learner's Dictionary of American English © 2025

M, m /ɛm/   n. [countable] , pl. Ms or M's, ms or m's. 

1. Linguistics the 13th letter of the English alphabet, a consonant.

M,  an abbreviation of:

1. Physics mach.
2. Biochemistry married.
3. medium.
4. mega-.

M,  Symbol.

1. the 13th in order or in a series.
2. the Roman numeral for 1000.

m,  an abbreviation of:

1. Physics mass.
2. medium.
3. Weights and Measures meter.
4. middle.

M.,  an abbreviation of:

1. majesty.
2. Music and Dance measure.
3. medicine.
4. medium.
5. meridian.
6. Monday.
7. Foreign Terms pl. MM. messieurs.

m.,  an abbreviation of:

1. male.
2. married.
3. masculine.
4. Physics mass.
5. medium.
6. Latin merīdiēs noon.
7. Weights and Measures meter.
8. middle.
9. Weights and Measures mile.
10. minute.
11. morning.

WordReference Random House Learner's Dictionary of American English © 2025

ˈRo•man ˈnu•mer•al,  n. [countable]

1. any of the numerals in the ancient Roman system of notation, still used occasionally. The basic symbols are I (=1), V (=5), X (=10), L (=50), C (=100), D (=500), and M (=1000).

WordReference Random House Unabridged Dictionary of American English © 2025

M, m  (em), n., pl. M's or Ms, m's or ms. 

1. Linguistics the thirteenth letter of the English alphabet, a consonant.
2. Linguistics any spoken sound represented by the letter M or m, as in my, summer, or him.
3. something having the shape of an M.
4. a written or printed representation of the letter M or m.
5. Printing a device, as a printer's type, for reproducing the letter M or m.
6. Printing em.

M, 

1. Physics mach.
2. Music and Dance major.
3. Electricity male.
4. Biochemistry married.
5. Medieval.
6. medium.
7. mega-.
8. Middle.
9. modal auxiliary.
10. modifier.
11. Economics, Business monetary aggregate: issued periodically by the Federal Reserve Board as various measures of money supply (M-1, M-1A, M-2, etc.). Cf. L. 
12. British Terms motorway (used with a road number to designate a major highway):
    the M1.

M, [Symbol.]

1. the thirteenth in order or in a series, or, when I is omitted, the twelfth.
2. (sometimes l.c.) the Roman numeral for 1000. Cf. Roman numerals. 
3. [Elect.] magnetization.
4. Biochemistry methionine.

m, 

1. Physics mass.
2. Business [Finance.] (of bonds) matured.
3. medieval.
4. medium.
5. Weights and Measures meter;
   meters.
6. middle.
7. [Music.] minor.

m, 

1. [Symbol, Elect.] magnetic pole strength.

M-, 

1. Military [U.S. Mil.] (used to designate the production model of military equipment, as the M-1 rifle.)

m-, 

1. meta-.

M'-, 

1. var. of Mac-. 

M., 

1. Majesty.
2. Place Names Manitoba.
3. markka;
   markkaa.
4. Marquis.
5. Music and Dance measure.
6. medicine.
7. medium.
8. meridian.
9. noon.
• Latin merīdiēs
10. Monday.
11. Foreign Terms pl MM. Monsieur.
12. mountain.

m., 

1. male.
2. Currency (in Germany) mark;
   marks.
3. married.
4. masculine.
5. Physics mass.
6. medium.
7. noon.
• Latin merīdiēs
8. Weights and Measures meter.
9. middle.
10. Weights and Measures mile.
11. minute.
12. Drugs (in prescriptions) mix.
• Latin merīdiēs
13. modification of.
14. modulus.
15. Chemistry molar.
16. month.
17. moon.
18. morning.
19. mouth.

WordReference Random House Unabridged Dictionary of American English © 2025

Ro′man nu′merals, 

1. the numerals in the ancient Roman system of notation, still used for certain limited purposes, as in some pagination, dates on buildings, etc. The common basic symbols are I (=1), V (=5), X (=10), L (=50), C (=100), D (=500), and M (=1000). The Roman numerals for one to nine are: I, II, III, IV, V, VI, VII, VIII, IX. A bar over a letter multiplies it by 1000;
   thus, X̄ equals 10,000. Integers are written according to these two rules: If a letter is immediately followed by one of equal or lesser value, the two values are added;
   thus, XX equals 20, XV equals 15, VI equals 6. If a letter is immediately followed by one of greater value, the first is subtracted from the second;
   thus, IV equals 4, XL equals 40, CM equals 900. Examples: XLVII(=47), CXVI(=116), MCXX(=1120), MCMXIV(=1914). Roman numerals may be written in lowercase letters, though they appear more commonly in capitals.

• 1725–35

WordReference Random House Unabridged Dictionary of American English © 2025

m-, +

1. Computing (referring esp. to the use of wireless electronic devices) mobile:
   m-commerce; m-business.

Collins Concise English Dictionary © HarperCollins Publishers::

M symbol

1. mach
2. medium (size)
3. mega-
4. mark(s)
5. million
6. (in Britain) motorway
7. (Roman numeral) 1000
   See Roman numerals

Collins Concise English Dictionary © HarperCollins Publishers::

M'- prefix

1. a variant of Mac-

Collins Concise English Dictionary © HarperCollins Publishers::

M. abbreviation

1. Majesty
2. (in titles) Member
3. million
4. Also: M (MM., MM) Monsieur

Etymology: (sense 4) French equivalent of Mr

Collins Concise English Dictionary © HarperCollins Publishers::

Mac-, Mc-, M'- prefix

1. (in surnames of Scottish or Irish Gaelic origin) son of: MacDonald, MacNeice

Etymology: from Goidelic mac son of; compare Welsh mab, Cornish mab

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m- prefix

1. short for meta-4

m- prefix

1. indicating the use of mobile-communications technology: m-banking