noun, often capitalized, often attributive
\ ˈem How to pronounce m (audio) \
plural m's or ms\ ˈemz How to pronounce m (audio) \

Definition of m

 (Entry 1 of 4)

1a : the 13th letter of the English alphabet
b : a graphic representation of this letter
c : a speech counterpart of orthographic m
2 : one thousand — see Table of Numbers
3 : a graphic device for reproducing the letter m
4 : one designated m especially as the 13th in order or class
5 : something shaped like the letter M

Definition of m (Entry 2 of 4)

1 male
2 manual
3 married
4 martyr
5 masculine
6 mass
7 measure
8 meridian
9 [Latin meridies] noon
10 meter
11 middle
12 mile
13 [Latin mille] thousand
14 milli-
15 minute
16 molal; molality
17 mole
18 month
19 moon
20 morning
21 muscle

Definition of M (Entry 3 of 4)

1 Mach
2 magnitude
3 March
4 May
5 medium
6 mega-
7 million
8 molar; molarity
9 monsieur

Definition of m- (Entry 4 of 4)


Examples of m in a Sentence

Noun a word that starts with an m a word that starts with m

First Known Use of m


before the 12th century, in the meaning defined at sense 1a

Keep scrolling for more

Learn More about m

Time Traveler for m

Time Traveler

The first known use of m was before the 12th century

See more words from the same century

Dictionary Entries near m








See More Nearby Entries 

Statistics for m

Cite this Entry

“M.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/m. Accessed 14 Apr. 2021.

Style: MLA
MLACheck Mark Icon ChicagoCheck Mark Icon APACheck Mark Icon Merriam-WebsterCheck Mark Icon

Keep scrolling for more

More Definitions for m



English Language Learners Definition of m

: the 13th letter of the English alphabet
: the Roman numeral that means 1,000


noun, often capitalized
\ ˈem How to pronounce m (audio) \
plural m's or ms\ ˈemz \

Kids Definition of m

1 : the 13th letter of the English alphabet
2 : 1000 in Roman numerals

Kids Definition of m.

1 male
2 meter
3 mile

Medical Definition of m

 (Entry 1 of 4)

1 Mach
2 male
3 married
4 masculine
5 mass
6 meter
7 [Latin mille] thousand
8 million
9 minim
10 minute
11 molal
12 molality
13 molar
14 molarity
15 mole
16 mucoid
17 muscle

Medical Definition of m- (Entry 2 of 4)



\ ˈem How to pronounce M (audio) \
plural M's or Ms

Medical Definition of M (Entry 3 of 4)

: an antigen of human blood that shares a common genetic locus with the N antigen

Medical Definition of M (Entry 4 of 4)

1 [Latin misce] mix used in writing prescriptions
2 mitosis — see m phase

More from Merriam-Webster on m

Nglish: Translation of m for Spanish Speakers

Britannica.com: Encyclopedia article about m

Comments on m

What made you want to look up m? Please tell us where you read or heard it (including the quote, if possible).


Test Your Vocabulary

The Exceptions Quiz III

  • one green toy robot amidst many red toy robots
  • Which of these words does not mean "nonsense"?
Spell It

Can you spell these 10 commonly misspelled words?

 AlphaBear 2

Spell words. Make bears.

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!