﻿---
title: Dictionary decompounder token filter
description: Uses a specified list of words and a brute force approach to find subwords in compound words. If found, these subwords are included in the token output...
url: https://www.elastic.co/elastic/docs-builder/docs/2532/reference/text-analysis/analysis-dict-decomp-tokenfilter
products:
  - Elasticsearch
---

# Dictionary decompounder token filter
<note>
  In most cases, we recommend using the faster [`hyphenation_decompounder`](https://www.elastic.co/elastic/docs-builder/docs/2532/reference/text-analysis/analysis-hyp-decomp-tokenfilter) token filter in place of this filter. However, you can use the `dictionary_decompounder` filter to check the quality of a word list before implementing it in the `hyphenation_decompounder` filter.
</note>

Uses a specified list of words and a brute force approach to find subwords in compound words. If found, these subwords are included in the token output.
This filter uses Lucene’s [DictionaryCompoundWordTokenFilter](https://lucene.apache.org/core/10_0_0/analysis/common/org/apache/lucene/analysis/compound/DictionaryCompoundWordTokenFilter.md), which was built for Germanic languages.

## Example

The following [analyze API](https://www.elastic.co/docs/api/doc/elasticsearch/operation/operation-indices-analyze) request uses the `dictionary_decompounder` filter to find subwords in `Donaudampfschiff`. The filter then checks these subwords against the specified list of words: `Donau`, `dampf`, `meer`, and `schiff`.
```json

{
  "tokenizer": "standard",
  "filter": [
    {
      "type": "dictionary_decompounder",
      "word_list": ["Donau", "dampf", "meer", "schiff"]
    }
  ],
  "text": "Donaudampfschiff"
}
```

The filter produces the following tokens:
```text
[ Donaudampfschiff, Donau, dampf, schiff ]
```


## Configurable parameters

<definitions>
  <definition term="word_list">
    (Required*, array of strings) A list of subwords to look for in the token stream. If found, the subword is included in the token output.
  </definition>
</definitions>

Either this parameter or `word_list_path` must be specified.
<definitions>
  <definition term="word_list_path">
    (Required*, string) Path to a file that contains a list of subwords to find in the token stream. If found, the subword is included in the token output.
  </definition>
</definitions>

This path must be absolute or relative to the `config` location, and the file must be UTF-8 encoded. Each token in the file must be separated by a line break.
Either this parameter or `word_list` must be specified.
<definitions>
  <definition term="max_subword_size">
    (Optional, integer) Maximum subword character length. Longer subword tokens are excluded from the output. Defaults to `15`.
  </definition>
  <definition term="min_subword_size">
    (Optional, integer) Minimum subword character length. Shorter subword tokens are excluded from the output. Defaults to `2`.
  </definition>
  <definition term="min_word_size">
    (Optional, integer) Minimum word character length. Shorter word tokens are excluded from the output. Defaults to `5`.
  </definition>
  <definition term="only_longest_match">
    (Optional, Boolean) If `true`, only include the longest matching subword. Defaults to `false`.
  </definition>
</definitions>


## Customize and add to an analyzer

To customize the `dictionary_decompounder` filter, duplicate it to create the basis for a new custom token filter. You can modify the filter using its configurable parameters.
For example, the following [create index API](https://www.elastic.co/docs/api/doc/elasticsearch/operation/operation-indices-create) request uses a custom `dictionary_decompounder` filter to configure a new [custom analyzer](https://docs-v3-preview.elastic.dev/elastic/docs-builder/docs/2532/manage-data/data-store/text-analysis/create-custom-analyzer).
The custom `dictionary_decompounder` filter find subwords in the `analysis/example_word_list.txt` file. Subwords longer than 22 characters are excluded from the token output.
```json

{
  "settings": {
    "analysis": {
      "analyzer": {
        "standard_dictionary_decompound": {
          "tokenizer": "standard",
          "filter": [ "22_char_dictionary_decompound" ]
        }
      },
      "filter": {
        "22_char_dictionary_decompound": {
          "type": "dictionary_decompounder",
          "word_list_path": "analysis/example_word_list.txt",
          "max_subword_size": 22
        }
      }
    }
  }
}
```