This element's attributes include theglobal attributes.

Thetitle attribute has special meaning, as noted below.

There are some not-entirely-obvious aspects to using the<dfn> element. We examine those here.

The term being defined is identified following these rules:

1. If the<dfn> element has atitle attribute, the value of thetitle attribute is considered to be the term being defined. The element must still have text within it, but that text may be an abbreviation (perhaps using<abbr>) or another form of the term.
2. If the<dfn> contains a single child element and does not have any text content of its own, and the child element is an<abbr> element with atitle attribute itself, then the exact value of the<abbr> element'stitle is the term being defined.
3. Otherwise, the text content of the<dfn> element is the term being defined. This is shownin the first example below.

If you include anid attribute on the<dfn> element, you can then link to it using<a> elements. Such links should be uses of the term, with the intent being that the reader can quickly navigate to the term's definition if they're not already aware of it, by clicking on the term's link.

This is shown in the example underLinks to definitions below.

Let's take a look at some examples of various usage scenarios.

This example uses a plain<dfn> element to identify the location of a term within the definition.

HTML

<p>  The <strong>HTML Definition element (<dfn>&lt;dfn&gt;</dfn>)</strong> is used  to indicate the term being defined within the context of a definition phrase  or sentence.</p>

Since the<dfn> element has notitle, the text contents of the<dfn> element itself are used as the term being defined.

Result

To add links to the definitions, you create the link the same way you always do, with the<a> element.

HTML

<p>  The  <strong>HTML Definition element (<dfn>&lt;dfn&gt;</dfn>)</strong>  is used to indicate the term being defined within the context of a definition  phrase or sentence.</p><p>  Lorem ipsum dolor sit amet, consectetur adipiscing elit. Graece donan, Latine  voluptatem vocant. Confecta res esset. Duo Reges: constructio interrete.  Scrupulum, inquam, abeunti;</p><p>  Because of all of that, we decided to use the  <code><a href="#definition-dfn">&lt;dfn&gt;</a></code> element for this  project.</p>

Here we see the definition — now with anid attribute,"definition-dfn", which can be used as the target of a link. Later on, a link is created using<a> with thehref attribute set to"#definition-dfn" to set up the link back to the definition.

Result

In some cases, you may wish to use an abbreviation for a term when defining it. This can be done by using the<dfn> and<abbr> elements in tandem, like this:

HTML

<p>  The <dfn><abbr title="Hubble Space Telescope">HST</abbr></dfn> is among the  most productive scientific instruments ever constructed. It has been in orbit  for over 20 years, scanning the sky and returning data and photographs of  unprecedented quality and detail.</p><p>  Indeed, the <abbr title="Hubble Space Telescope">HST</abbr> has arguably done  more to advance science than any device ever built.</p>

Note the<abbr> element nested inside the<dfn>. The former establishes that the term is an abbreviation ("HST") and specifies the full term ("Hubble Space Telescope") in itstitle attribute. The latter indicates that the abbreviated term represents a term being defined.

Result

• Elements related to definition lists:<dl>,<dt>,<dd>
• <abbr>