Punctuation mark (–) that can be used singly or in pairs (as a type of parenthesis, to mark off a clearly subordinate part of a sentence). A single dash is used to represent a sudden break or interruption in dialogue or an abrupt change of subject.

A punctuation mark (—) used to indicate a break or interruption in a sentence. It is named for the em, a typographical unit of measure that in some fonts equals the width of a capital M. Compare en dash, hyphen.