From http://reference.sitepoint.com/html/dfn:
Note that dfn is short for defining instance, not for definition—you
should not place the actual definition of the term between the opening
<dfn> and closing </dfn> tags.
<dt>dfn</dt>
<dd>I wonder how much my silly definition of happiness:
- <dfn>
- Happiness is the limit of our mood function when “how I currently feel” approaches
+ <blockquote>
+ <dfn>Happiness</dfn> is the limit of our mood function when “how I currently feel” approaches
to “how I want to feel”
- </dfn>
+ </blockquote>
is flawed...
</dd>