@asgeirtj: You'll have to use inflection tags. Here's an example from the Dune fictionary:
Code:
<idx:entry scriptable="yes">
<idx:orth value="Fleur de Lys">
<idx:infl>
<idx:iform name="" value="Ly"/>
<idx:iform name="plural" value="Lys"/>
<idx:iform name="plural" value="Lyes"/>
<idx:iform name="" value="Fleur"/>
<idx:iform name="plural" value="Fleurs"/>
<idx:iform name="plural" value="Fleures"/>
</idx:infl>
</idx:orth><h2> Fleur de Lys </h2> <b>
<font size="7">— </font></b><br>Fleur de Lys was a strategy game much enjoyed by Vorian Atreides.<br><br><b>Appearances</b><br><br>• Dune: The Machine Crusade "<br><br>
</idx:entry>