DOCBOOK: Markup for definitions

[Joachim Ziegler <ziegler@algorilla.de>]

Suppose I write a sentence like

"A *process* is a programm in execution."

The word "process" should be emphasized in both the HTML and the PDF version.

Later, whenever I speak of "processes", I want to have a link to the 
definition above (in the HTML version). Moreover, the word "process" should 
show up in the index.

What's the correct markup for this? 

Greetings,
Joachim