noun, plural ems.

the letter M, m.
Also called mut, mutton. Printing.
  1. the square of any size of type used as the unit of measurement for matter printed in that type size.
  2. (originally) the portion of a line of type occupied by the letter M in type of the same size.


Printing. having the area of an em quad or the length of an em dash.

Origin of em

First recorded in 1860–65


Symbol, Physical Chemistry.


electronic mail.
electron microscope; electron microscopy.
end matched.
Engineer of Mines.
enlisted man; enlisted men.


[uh m]

pronoun Informal.

them: Put 'em down there.

Origin of 'em

1350–1400; Middle English hem, Old English heom, dative and accusative plural of he1



variant of en-1 before b, p, and sometimes m: embalm.
Compare im-1.



variant of en-2 before b, m, p, ph: embolism, emphasis.


Earl Marshal.
Engineer of Mines.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for em

Contemporary Examples of em

Historical Examples of em

  • I didnt see any mention of em in your report of last nights proceedings.

    Spawn of the Comet

    Harold Thompson Rich

  • We'll keep to ourselves and pay no attention to em no more'n if they wa'n't there.

    The Woman-Haters

    Joseph C. Lincoln

  • I had my fingers in his pocket, and he clapped his hand on em, and catched me!

  • Then one of em replyd, Governor, you are a Lyar, and guilty of that Infamy.

  • Before Em left town he and she had been engaged "on approval."

    In a Little Town

    Rupert Hughes

British Dictionary definitions for em


noun printing

Also called: mutton, mut the square of a body of any size of type, used as a unit of measurement
Also called: pica em, pica a unit of measurement used in printing, equal to one sixth of an inch

Word Origin for em

C19: from the name of the letter M



before b, m, and p, a variant of en- 1, en- 2



an informal variant of them
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for em



representing Latin ex- assimilated to following -m- (see ex-).



from French assimilation of en- to following labial (see en- (1)). Also a prefix used to form verbs from adjectives and nouns.


Middle English, now taken as a colloquial abbreviation of them, but originally a form of hem, dative and accusative of the third person plural pronoun.

Online Etymology Dictionary, © 2010 Douglas Harper

em in Medicine



electron microscope



Variant ofen-
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.