Definition List: Definition

This element is used in two senses:

  1. Within a two-part list (<def-list>), <def> contains the definition, description, or other explanation of a word, phrase, or picture. In this usage, <def> is half of a <term>/<def> pair within an item (<def-item>) in the definition list.
  2. Within an <abbrev> element, <def> contains the definition or expansion of an abbreviation or acronym.


The term <term> part of an item in a two-part (definition) list may be a term, a word, a phrase, a picture or icon, an equation, a variable, or anything else that is to be explained. The definition <def> part of an item in a two-part (definition) list need not be a “definition” in the strict dictionary sense of that word. Such a definition could be a discussion, explanation, expansion, or just a few words that tell the reader about the <term>. When a <def-list> is within a <glossary> element, the definitions are assumed to be real definitions.


id Identifier
rid Reference to an Identifier

Related Elements

A <def-list> may have a <title> naming the entire list, followed by optional headings for terms and their definitions. <term-head> contains the heading over the first (term) column, and <def-head> contains the heading for the second (definition) column; neither serves as a container element for terms or definitions. Individual <term>s and their <def>s are paired in <def-item>s.

Content Model

<!ELEMENT  def          %def-model;                                  >

Expanded Content Model



Any one of:

This element may be contained in:

<abbrev>, <def-item>


<glossary id="bid.1237">
<term id="bid.1238">3-D or 3D</term>
<term id="bid.1722">Accession number</term>
<p>An Accession number is a unique identifier given 
to a sequence when it is submitted to one of the DNA 
repositories (GenBank, EMBL, DDBJ). The initial 
deposition of a sequence record is referred to as 
version 1. If the sequence is updated, the version 
number is incremented, but the Accession number will 
remain constant.</p>