em
/ɛm/
noun
- The letter M.
- The first letter of his name is an em.
- She wrote a capital em on the board.
- Spell 'mom' with two ems.
- A unit of measurement in printing, equal to the width of the letter M in a particular typeface.
- Set the left margin to two ems.
- The paragraph was indented by one em.
- In typography, an em dash is the width of an em.