# Defining Synonyms

By means of the thesaurus function of the Autonomy search engine, synonyms can be defined. This makes it possible to get hits even if only a term with a similar meaning (a synonym) instead of the search term itself can be found in the content.

A thesaurus can be defined and installed in the following way:

1. Define the thesaurus as a text file, `vdk30.txt`. Example:

```\$control:1
synonyms:
{
list: "publication,magazine,newspaper,journal"
list: "law,statute,bill"
}
\$\$
```

The definition consists of synonym lists, each of them occupying an individual line.

2. Compile the thesaurus using `mksyd`. If you are using the `uni` locale, the following steps are required under Linux:

```> export PATH=\$PATH:installation_dir/3rdparty/vdk/_ilnx21/bin
> export LD_LIBRARY_PATH=\$LD_LIBRARY_PATH:installation_dir/3rdparty/vdk/_ilnx21/bin
> mksyd -locale uni -f vdk30.txt -syd vdk30.syd
```

Unter Windows you can extend the search path using

```set PATH=%PATH%;installation_dir\3rdparty\vdk\_ilnx21\bin
```

Then execute the command given above.

3. To install the thesaurus, please copy it to the location where the search engine expects it to be:

```> cp vdk30.syd Installationsverzeichnis/3rdparty/vdk/common/uni
```

Under Windows, please use `copy` instead of `cp` and replace the slashes with backslashes.

4. Restart the SES:

```> installation_dir/instance/instance_name/bin/rc.npsd restart SES
```

The defined synonyms can now be used in search queries made with the `THESAURUS` operator. Example: the search query

```<#MANY><#THESAURUS>"publication"
```

will find all documents containing the word "publication" or one of its synonyms.