About
dfn 1) is an HTML element that locates the definition of a term and can be addressed as fragment in an URI.
You can navigate to it by giving it in the fragment of an URI.
Example
Inline
The below phrase 2) define the term represent.
<p>
Elements in the DOM <dfn id="represents">represent</dfn> things;
that is, they have intrinsic <em>meaning</em>, also known as semantics.
</p>
Glossary
With a description list inside the description term (dt).
<dl>
<!-- Entry -->
<dt><dfn>happiness</dfn></dt>
<dd>The state of being happy.</dd>
<!-- Entry -->
<dt><dfn>rejoice</dfn></dt>
<dd>To be delighted oneself.</dd>
</dl>