> ## Documentation Index
> Fetch the complete documentation index at: https://algolia.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Customize word segmentation

> Learn how to customize word segmentation (decompounding) dictionaries through the dashboard.

export const SearchQuery = () => <Tooltip tip="The text users enter into a search box. In the Search API, this corresponds to the query parameter. A search query is often used with filters, facets, and other parameters, but these aren't part of the query text itself.">
    search query
  </Tooltip>;

export const Records = () => <Tooltip tip="A record is a searchable object in an Algolia index. Each record consists of named attributes." cta="Algolia records" href="/doc/guides/sending-and-managing-data/prepare-your-data#algolia-records">
    records
  </Tooltip>;

export const Index = () => <Tooltip tip="An Algolia index is a searchable dataset that consists of records and configuration settings. These settings define how the records are searched and ranked.">
    index
  </Tooltip>;

export const Application = () => <Tooltip tip="An Algolia application is a self-contained environment with its own indices, configuration, and API keys. Applications don't share data or settings with each other.">
    application
  </Tooltip>;

Word segmentation, also known as decompounding, is the process of splitting a word into its constituent parts. Decompounding is crucial for languages that have many compound words. For example, Algolia splits the Dutch word "eettafel" (dining table) into "eet" and "tafel." Decompounding allows the engine to find more results by searching for a word's constituents and their alternatives.

You can enable decompounding on your <Records /> by using the [`decompoundedAttributes`](/doc/api-reference/api-parameters/decompoundedAttributes) setting.
This setting requires you to specify the attributes to decompound and the language or languages to use.
Decompounding is enabled by default on the <SearchQuery /> as long as [`queryLanguages`](/doc/api-reference/api-parameters/queryLanguages) is properly set.

Decompounding relies on language-specific dictionaries, which Algolia maintains for German, Dutch, Finnish, Swedish, Danish, and Norwegian. While Algolia updates these dictionaries regularly, you can also customize them for your use case.

**Algolia applies segmentation dictionaries at the <Application /> rather than the <Index /> level.**
Any customizations on a language's segmentation dictionary affect all indices on your application with [`queryLanguages`](/doc/api-reference/api-parameters/queryLanguages) set to that language and
[`decompoundedAttributes`](/doc/api-reference/api-parameters/decompoundedAttributes) enabled.

<Note>
  You should use [`decompoundedAttributes`](/doc/api-reference/api-parameters/decompoundedAttributes) and other language-specific features in conjunction with the [`queryLanguages`](/doc/api-reference/api-parameters/queryLanguages) setting. Refer to the [guide on how to set an index's query language](/doc/guides/managing-results/optimize-search-results/handling-natural-languages-nlp/how-to/how-to-set-an-index-query-language) to learn more.
</Note>

## Inspecting out-of-the box segmentation

You may be curious to see how the engine segments a particular word. Using the dashboard, you can enter it to see how the engine interprets it in a given language, using segmentation.

1. Go to the [**Dictionaries** page](https://dashboard.algolia.com/dictionaries/segmentation) in the left sidebar menu of the dashboard.
2. Search for and select the language whose segmentation rules you want to inspect on the screen's top right. **Segmentation dictionaries are language-specific.**
3. Select the **Words Segmentation** dictionary.
4. Enter a word into the input bar. **You can't use spaces in this input.**
5. Below, under **Algolia segmentation**, the dashboard displays how the engine interprets the word. If it segments the word, the dashboard displays its constituent parts below. If it doesn't, the dashboard displays that the word is **being kept as it is**.

## Creating new segmentation rules

You may find that Algolia doesn't segment a word you would expect to. This can particularly be true if a compound word includes a brand name or proper noun. For example, the engine doesn't automatically segment the Dutch word "gyprocplaten" (drywall). This means it only returns exact matches, while you may also want results to include results with either "gyproc" or "platen" and its alternatives. In this case, you should create a new segmentation entry.

1. Go to the [**Dictionaries** page](https://dashboard.algolia.com/dictionaries/segmentation) in the left sidebar menu of the dashboard.
2. Search for and select the language whose segmentation rules you want to inspect on the screen's top right. **Segmentation dictionaries are language-specific.**
3. Select the **Words Segmentation** dictionary.
4. Enter a word into the input bar. **You can't use spaces in this input.**
5. Below, under **Algolia segmentation**, the dashboard displays how the engine interprets the word. Select the **Edit** button to the right. An input will appear below with the word from the input autofilled.
6. Select **Split** as the **Action** and enter the constituent parts you expect under **Output**. In the "gyprocplaten" example, the constituent parts are "gyproc" and "platen".
7. Select **Review and Save** to save this and any other changes.

## Disabling segmentation

You may find that Algolia segments a word you wouldn't expect. For example, the engine automatically segments the German brand "Volkswagen" as "volks" and "wagen". But as this is a brand name, it shouldn't be segmented for the most relevant results. In this case, you can turn off segmentation for this entry.

1. Go to the [**Dictionaries** page](https://dashboard.algolia.com/dictionaries/segmentation) in the left sidebar menu of the dashboard.
2. Search for and select the language whose segmentation rules you want to inspect on the screen's top right. **Segmentation dictionaries are language-specific.**
3. Select the **Words Segmentation** dictionary.
4. Enter a word into the input bar. **You can't use spaces in this input.**
5. Below, under **Algolia segmentation**, the dashboard displays how the engine interprets the word. Select the **Edit** button to the right. An input will appear below with the word from the input auto-filled.
6. Select **Keep as is** as the **Action**.
7. Select **Review and Save** to save this and any other changes.

## Uploading and downloading customizations

You may have curated your own list of custom segmentation for your use case. You can upload them in bulk in either CSV or JSON format using the **Actions** button with the gear icon.

See the expected formats below.

### CSV format

```csv CSV theme={"system"}
word, decomposition, language, objectID
gyprocplaten,"gyproc,platen",nl,1
volkswagen,"volkswagen",de,2
```

### JSON format

```json JSON icon=braces theme={"system"}
[
  {
    "word":"gyprocplaten",
    "decomposition":["gyproc", "platen"],
    "language":"nl",
    "objectID":"1"
  },
  {
    "word":"volkswagen",
    "decomposition":["volkswagen"],
    "language":"de",
    "objectID":"2"
  }
]
```

Using the **Actions** button, you can also download all custom alternatives from a dictionary, either in CSV or JSON format. You may choose to do this regularly to keep track of alternatives you added at a particular time.