# Synonym Lists

> Use thesaurus files with TX Spell .NET in Windows Forms: the .dat and .idx format, available languages, SynonymLanguage (Auto) and SynonymList in code.

- **Product:** TX Spell .NET for Windows Forms
- **Section:** Documentation
- **Kind:** Topic
- **Path:** TX Spell .NET for Windows Forms > Synonyms and Thesaurus > Synonym Lists
- **1684 words**
- **Web URL:** https://docs.textcontrol.com/tx-spell-dotnet-winforms/synonyms/lists/
- **LLMs URL:** https://docs.textcontrol.com/tx-spell-dotnet-winforms/synonyms/lists/llms.txt
- **LLMs-Full URL:** https://docs.textcontrol.com/tx-spell-dotnet-winforms/synonyms/lists/llms-full.txt

---

The synonyms of TX Spell .NET come from *synonym lists*, thesaurus files in the open source format of OpenOffice, one list per language. The NuGet packages bring the list for US English; lists for 23 more languages and regions are part of the language archives Text Control offers for download. The same spell checker that checks spelling loads them and chooses the list for the language of a text.

### What a Synonym List Is

A synonym list is a pair of files with the same name:

| File | Holds |
|---|---|
| *.dat* | The entries: for each word, its meanings, one line each, with the part of speech and the synonyms |
| *.idx* | An index of all words, with the position of each entry in the *.dat* file |

The first line of both files names their encoding, such as `UTF-8`. An entry of the US English list looks like this; each line after the word is one meaning:

```text
house|14
(noun)|dwelling (generic term)|home (generic term)|domicile (generic term)|...
(verb)|put up|domiciliate|shelter (generic term)
```

Notes such as `(generic term)`, `(similar term)` or `(antonym)` describe how a synonym relates to the word. The names of the files start with `th_` or `thes_`, followed by the locale, such as *th\_en\_US\_v2.dat* and *th\_en\_US\_v2.idx*; TX Spell .NET takes the language of a list from this name.

### Where the Files Are

TX Spell .NET reads synonym lists from the folder *SynonymLists*, next to the application or, on the development machine, below the *Assembly* folder of the installation. The NuGet package copies the folder with the US English list, *th\_en\_US\_v2.dat* and *th\_en\_US\_v2.idx*, into the output folder when you build, and [SynonymListsDirectoryPath](https://docs.textcontrol.com/tx-spell-dotnet-winforms/reference/txtextcontrol-proofing/txspellchecker/synonymlistsdirectorypath-property/llms-full.txt) sets another folder; [Installing Dictionaries and Language Data](https://docs.textcontrol.com/tx-spell-dotnet-winforms/installation/language-data/llms-full.txt) describes the four language data folders together. [AvailableSynonymLists](https://docs.textcontrol.com/tx-spell-dotnet-winforms/reference/txtextcontrol-proofing/txspellchecker/availablesynonymlists-property/llms-full.txt) returns the names of the lists in the folder, such as `th_en_US_v2.dat`.

### Get Lists for Other Languages

The language archives on the dictionary download page contain a folder *SynonymLists* when the language has a thesaurus; the column "Thesaurus" of [Supported Languages](https://docs.textcontrol.com/tx-spell-dotnet-winforms/overview/languages/#languages-and-their-data) shows which ones do.

Copy the *.dat* and *.idx* files of a list into the *SynonymLists* folder of your project and set their **Copy to Output Directory** property, or add this to the project file for every file in the folder:

```xml
<ItemGroup>
  <None Update="SynonymLists\*.*" CopyToOutputDirectory="PreserveNewest" />
</ItemGroup>
```

Most lists come with license or readme files in their folder, whose terms apply when you ship them. [Hunspell and OpenOffice Dictionaries](https://docs.textcontrol.com/tx-spell-dotnet-winforms/dictionaries/hunspell/llms-full.txt) describes the archives.

### How a List Is Chosen

[SynonymLanguage](https://docs.textcontrol.com/tx-spell-dotnet-winforms/reference/txtextcontrol-proofing/txspellchecker/synonymlanguage-property/llms-full.txt) chooses the default synonym list. Its default, "(Auto)", takes the list in the language of the default spell checking dictionary: with the German dictionary as the default, the German list. When the folder has no list of that language, the spell checker takes one of a close language, then one of the language the application runs in, then the US English list and, without one, the first list of the folder.

To fix the list instead, set `SynonymLanguage` to its name, such as `"th_de_DE_v2.dat"`; "(none)" loads no list. A name the folder doesn't have resets the property to "(Auto)", and a folder without any list resets it to "(none)". The chosen list has its [IsSelectedAsDefault](https://docs.textcontrol.com/tx-spell-dotnet-winforms/reference/txtextcontrol-proofing/synonymlist/isselectedasdefault-property/llms-full.txt) property set to `true`.

### Load a List in Code

The lists the spell checker uses are in [SynonymLists](https://docs.textcontrol.com/tx-spell-dotnet-winforms/reference/txtextcontrol-proofing/txspellchecker/synonymlists-property/llms-full.txt), a [SynonymListCollection](https://docs.textcontrol.com/tx-spell-dotnet-winforms/reference/txtextcontrol-proofing/synonymlistcollection/llms-full.txt). To add a list, create a [SynonymList](https://docs.textcontrol.com/tx-spell-dotnet-winforms/reference/txtextcontrol-proofing/synonymlist/llms-full.txt) with the name of its file and pass it to [Add](https://docs.textcontrol.com/tx-spell-dotnet-winforms/reference/txtextcontrol-proofing/synonymlistcollection/add-method/llms-full.txt):

```csharp
// Offer German synonyms as well as English ones
TXTextControl.Proofing.SynonymList german = new TXTextControl.Proofing.SynonymList("th_de_DE_v2.dat");
txSpellChecker1.SynonymLists.Add(german);
```

The code works as follows:

- The [constructor](https://docs.textcontrol.com/tx-spell-dotnet-winforms/reference/txtextcontrol-proofing/synonymlist/constructor/llms-full.txt) takes the name of the *.dat* or *.idx* file. A name without a path refers to the default folder.
- `Add` loads the list and throws an `ArgumentException` when a file is missing.
- The list gets its [Language](https://docs.textcontrol.com/tx-spell-dotnet-winforms/reference/txtextcontrol-proofing/synonymlist/language-property/llms-full.txt) from the file name, here German (Germany).

[GetItem](https://docs.textcontrol.com/tx-spell-dotnet-winforms/reference/txtextcontrol-proofing/synonymlistcollection/getitem-method/llms-full.txt) finds a list by its [Name](https://docs.textcontrol.com/tx-spell-dotnet-winforms/reference/txtextcontrol-proofing/synonymlist/name-property/llms-full.txt), such as `"th_de_DE_v2.dat"`, and [Remove](https://docs.textcontrol.com/tx-spell-dotnet-winforms/reference/txtextcontrol-proofing/synonymlistcollection/remove-method/llms-full.txt) takes it out again. To keep a list loaded but unused, set its [IsCreateSynonymsEnabled](https://docs.textcontrol.com/tx-spell-dotnet-winforms/reference/txtextcontrol-proofing/synonymlist/iscreatesynonymsenabled-property/llms-full.txt) property to `false`.

### Lists in the User Interface

- **The options dialog.** Its **Thesaurus** tab lists the synonym lists of the spell checker, and the user switches a list on and off for synonyms there. [DisplayName](https://docs.textcontrol.com/tx-spell-dotnet-winforms/reference/txtextcontrol-proofing/synonymlist/displayname-property/llms-full.txt) sets the name the dialog shows. [Options Dialog](https://docs.textcontrol.com/tx-spell-dotnet-winforms/user-interface/options-dialog/#the-hyphenation-and-thesaurus-tabs) describes the tab.

    ![The Options dialog over TX Text Control Words with the tabs Spell Checking Options, Spell Checking Dictionaries, Hyphenation and Thesaurus.](https://docs.textcontrol.com/assets/img/tx-spell-dotnet-winforms/options-dialog-dictionaries.40842cf9.webp)
- **The ribbon.** The **Settings** group of the **Proofing** tab of a [RibbonProofingTab](https://docs.textcontrol.com/tx-text-control-dotnet-winforms/reference/txtextcontrol-windows-forms-ribbon/ribbonproofingtab/llms-full.txt) has a **Load Thesaurus File** button, which opens a dialog for loading thesaurus files (*.dat*) to create synonyms.

    ![The Proofing tab of the ribbon with the buttons Thesaurus in the Spelling & Hyphenation group and Load Thesaurus File in the Settings group.](https://docs.textcontrol.com/assets/img/tx-spell-dotnet-winforms/ribbon-proofing-tab.748b5cc8.webp)

### Next Steps

- [Synonyms in the Context Menu](https://docs.textcontrol.com/tx-spell-dotnet-winforms/synonyms/context-menu/llms-full.txt): the thesaurus in TX Text Control.
- [Looking Up Synonyms in Code](https://docs.textcontrol.com/tx-spell-dotnet-winforms/synonyms/in-code/llms-full.txt): create synonyms for any word.
- [Installing Dictionaries and Language Data](https://docs.textcontrol.com/tx-spell-dotnet-winforms/installation/language-data/llms-full.txt): ship the lists with your application.

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## Nearby

- **Previous:** [Synonyms and Thesaurus](https://docs.textcontrol.com/tx-spell-dotnet-winforms/synonyms/llms-full.txt)
- **Next:** [Synonyms in the Context Menu](https://docs.textcontrol.com/tx-spell-dotnet-winforms/synonyms/context-menu/llms-full.txt)