Cross-language information retrieval (CLIR) is a subfield of information retrieval dealing with retrieving information written in a language different from the language of the user's query. For example, a user may pose their query in English but retrieve relevant documents written in French. To do so, most of CLIR systems use translation techniques. CLIR techniques can be classified into different categories based on different translation resources:Dictionary-based CLIR techniques
Parallel corpora based CLIR techniques
Comparable corpora based CLIR techniques
Machine translator based CLIR techniques
The first workshop on CLIR was held in Zürich during the SIGIR-96 conference. Workshops have been held yearly since 2000 at the meetings of the Cross Language Evaluation Forum (CLEF).
The term "cross-language information retrieval" has many synonyms, of which the following are perhaps the most frequent: cross-lingual information retrieval, translingual information retrieval, multilingual information retrieval. The term "multilingual information retrieval" refers to CLIR in general, but it also has a specific meaning of cross-language information retrieval where a document collection is multilingual.
Google Search had a cross-language search feature that was removed in 2013.