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em dash vs. en dash
There are two similar but distinct punctuation marks called dashes: the en dash ( – ) and the em dash ( — ). In appearance, an en dash is slightly longer than a hyphen ( - ), approximately the width of a capital N, while an em dash is slightly longer than an en dash, approximately the width of a capital M (hence their names).
When we refer to dashes, we are usually referring to em dashes, as they are the more common punctuation mark of the two. However, it’s important to know the different ways that each mark is used.
en·dashor en dash (ĕn′dăsh′)
A symbol ( - ) used in writing or printing to connect continuing or inclusive numbers or to connect elements of a compound adjective when either of the elements is an open compound, as 1880-1945 or Princeton-New York trains.
[From its being the width of an n in printing.]
en dash(ˈɛnˌdæʃ) or
(Printing, Lithography & Bookbinding) printing a dash (–) one en long
a dash one en long.
See also related terms for punctuation.