Abstract: Methods, systems, and apparatus, including computer programs encoded on computer storage media, for query synonym expansion. One method includes receiving a query including a first compound term, and in response to receiving the query, performing the following operations before search results responsive to the query are identified: generating one or more splits of the first compound term, wherein each split divides the compound term into two or more subterms, assigning a score to each subterm of each split, determining an overall score for each split from the scores for the subterms of the split, selecting one or more of the one or more splits according to the overall score for each split, and augmenting the query with the subterms of each selected split.

Abstract: Methods, systems, and apparatus, including computer programs encoded on computer storage media, for identifying synonyms. One method includes receiving a query containing a first phrase, identifying one or more first synonym phrases that are synonyms for the first phrase, identifying a new synonym phrase that is a synonym for one of the first synonym phrases, determining that the new phrase is a synonym for the first phrase, and augmenting the query with the new phrase. Another method includes receiving a query including a first compound term having a first subterm, identifying a first synonym for a first subterm, generating a second compound term, wherein the second compound term is the first compound term modified by replacing the first subterm with the first synonym, and augmenting the query with the second compound term.

Abstract: Methods, systems, and apparatus, including computer programs encoded on computer storage media, for query synonym expansion. One method includes receiving a query including a first compound term, and in response to receiving the query, performing the following operations: generating one or more splits of the first compound term, assigning a score to each subterm of each split, determining an overall score for each split from the scores for the subterms of the split, selecting a first split from the one or more splits according to the overall score for each split, and augmenting the query with a first synonym phrase that is a synonym of a first subterm of the first split.