em

1 of 3

noun

1
: the letter m
2
: the width of a piece of type about as wide as it is tall used as a unit of measure of typeset matter

EM

2 of 3

abbreviation

1
electromagnetic
2
electron microscope; electron microscopy
3
end matched
4
engineer of mines
5
enlisted man

em-

3 of 3

prefix

see en-

Word History

First Known Use

Noun

13th century, in the meaning defined at sense 1

Time Traveler
The first known use of em was in the 13th century

Dictionary Entries Near em

Cite this Entry

“Em.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/em. Accessed 19 Mar. 2024.

Kids Definition

em-

see en-

Medical Definition

EM

abbreviation
1
electromagnetic
2
electron microscope; electron microscopy
3
emergency medicine
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