Enter the <dterm> element into the glossary as shown:
<glossary> . . . <dterm>word or phrase Definition of the term . . .
Be sure to keep the <dterm>words and phrases sorted within the glossary.
Here's part of a glossary that includes the definition of the term SGML:
<glossary> . . . <dterm>SGML Standard Generalized Markup Language. An international standard [ISO 8859: 1986] that establishes a method for information interchange. SGML describes constructs for marking the structure of information separate from its intended presentation or format.