Inside the Algolia Engine: Handling synonyms | Algolia

Synonyms play a crucial role in enhancing search engine results by introducing domain-specific knowledge. They allow for tuning search outcomes without making significant changes to records. However, handling synonyms, especially multi-word expressions, can be complex due to the need to manage proximity measures between matched words. Algolia's engine supports both 1-way and N-way synonyms, which can contain any type of expression (single or multiple words). The most useful synonyms are always very specific to a particular domain. The implementation of synonyms in the Algolia engine is fully done at search time to ensure an exact computation of relevance. This involves rewriting matched word positions for accurate proximity measures between matched words. Handling synonyms correctly in an instant search use case can be complex, and most engines fall short in this respect due to poor processing. Algolia's engine considers the last word of a synonym expression as allowed to match as a prefix, reducing flickering of search results. The configuration of synonyms is a key aspect of search relevance and should be configured in most use cases. Algolia continues to improve its handling of synonyms, with plans for hybrid indexing of multi-word synonyms to enhance performance.