The dash is a family of punctuation marks which are not part of a word, but resemble long hyphens in appearance.
The most common kinds of dash are the en dash (–) and the em dash (—).
For more information on the kinds of dashes and their usages, see the Wikipedia page Dash.
If your question is about a dash-like punctuation mark that is part of a word (such as in dash-like), it is not a dash. Use hyphen instead.