Steps
- Use the KB http://support.microsoft.com/kb/837847
- The "Office Sharepoint Server Search" is the service that uses the thesauraus ts*.xml files.
- There is a file tsneu.xml that is used for search. This is case if your language is neutral. Change the appropriate ts*.xml file.
- You have to find the right location for tsneu.xml. The easiest way to find the location is to use FileMon.exe.
- Set this filter in "C:\Program Files\Microsoft Office Servers\12.0\Data\*.xml" in the filemon.exe. The results will look like below.

- C:\Program Files\Microsoft Office Servers\12.0\Data\Office Server\Applications\829dd501-3ad7-4e27-88a6-67721fab8d4a\Config
- Now change the tsneu.xml as below. I added "Sales" and "Kumaran" as synonyms.
Original File
Changed File
<XML ID="Microsoft Search Thesaurus">
<thesaurus xmlns="x-schema:tsSchema.xml">
<diacritics_sensitive>0</diacritics_sensitive>
<expansion>
<sub>Internet Explorer</sub>
<sub>IE</sub>
<sub>IE5</sub>
</expansion>
<replacement>
<pat>NT5</pat>
<pat>W2K</pat>
<sub>Windows 2000</sub>
</replacement>
<expansion>
<sub>run</sub>
<sub>jog</sub>
</expansion>
</thesaurus>
<XML ID="Microsoft Search Thesaurus">
<thesaurus xmlns="x-schema:tsSchema.xml">
<diacritics_sensitive>0</diacritics_sensitive>
<expansion>
<sub>Internet Explorer</sub>
<sub>IE</sub>
<sub>IE5</sub>
</expansion>
<replacement>
<pat>NT5</pat>
<pat>W2K</pat>
<sub>Windows 2000</sub>
</replacement><expansion>
<sub>run</sub>
<sub>jog</sub>
</expansion>
<expansion><sub>sales</sub>
<sub>kumaran</sub>
</expansion>
</thesaurus>
</XML>
8. Save this tsnue.xml to location found with the Filemon.exe tool.
9. Start the "Office Sharepoint Server Search" service
That's It !! . You can see the results of searching "kumaran" bring up all the sales results.
Image 2 gives the orginal "sales" results.
Image 1:

Image 2 :
