# Cross Cluster Replication of Synonyms Sets

**URL:** <https://discuss.elastic.co/t/cross-cluster-replication-of-synonyms-sets/381527>\
**Category:** Elastic Search\
**Created:** [September 2, 2025, 5:00pm UTC](https://discuss.elastic.co/t/cross-cluster-replication-of-synonyms-sets/381527 "2025-09-02T17:00:27Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Droidrcc](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/droidrcc/32/144855_2.png) [@Droidrcc](https://discuss.elastic.co/u/Droidrcc)\
**Post date:** [September 2, 2025, 5:00pm UTC](https://discuss.elastic.co/t/cross-cluster-replication-of-synonyms-sets/381527/1 "2025-09-02T17:00:27Z")

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Hi!

I’ve been looking into the new [Elasticsearch Synonyms API](https://www.elastic.co/docs/api/doc/elasticsearch/operation/operation-synonyms-put-synonym?utm_source=chatgpt.com) for managing synonyms sets, and I was wondering about its compatibility with CCR (Cross-Cluster Replication).

Specifically:

- Is it possible to replicate synonym sets across clusters using CCR?

- If not directly supported, are there recommended approaches or workarounds to ensure synonym sets remain synchronized between leader and follower clusters?

Any insights, best practices, or official guidance would be really appreciated! I know I could update all clusters with the same set, but it means I have to keep them in sync from the application, and it is not ideal.

Thanks in advance.

> **[Create or update a synonym set | Elasticsearch API documentation](https://www.elastic.co/docs/api/doc/elasticsearch/operation/operation-synonyms-put-synonym)**
>
> Synonyms sets are limited to a maximum of 10,000 synonym rules per set.
> If you need to manage more synonym rules, you can create multiple synonym sets.
> When an existing synonyms...

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**Author:** ![Kathleen\_DeRusso](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/kathleen_derusso/32/132039_2.png) [@Kathleen\_DeRusso](https://discuss.elastic.co/u/Kathleen_DeRusso)\
**Post date:** [September 8, 2025, 12:10pm UTC](https://discuss.elastic.co/t/cross-cluster-replication-of-synonyms-sets/381527/2 "2025-09-08T12:10:20Z")

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Hi @Droidrcc , synonyms sets are backed by underlying system indices, which are a [known limitation](https://www.elastic.co/docs/deploy-manage/tools/cross-cluster-replication?utm_source=chatgpt.com#ccr-limitations)for CCR. Thus synonyms sets cannot be replicated using CCR. We are launching a new synoynms UI that should make synonyms easier to manage, but otherwise you probably need to enforce consistency in the client updating the synonyms.