4. The method of claim 3 , where each phrase is a search query from a query log.
3. The method of claim 1 , wherein determining one or more synonym pairs comprises: computing a translation likelihood for a phrase and a corresponding translated phrase; generating a synonym pair from a term in the phrase and a corresponding translated term in the corresponding translated phrase; assigning a score to the synonym pair, wherein the score is derived from the translation likelihood of the phrase and the corresponding translated phrase; and determining that the term and the corresponding translated term are synonyms using the assigned score of the synonym pair.