16. The method of claim 15 , further comprising: determining, after identifying the extra term as significant when the pair of queries is associated with at least the threshold quantity of search results that are different between the pair of the queries, whether a context exists in which the extra term is not significant.
16. The method of claim 15 , further comprising: determining, after identifying the extra term as significant when the pair of queries is associated with at least the threshold quantity of search results that are different between the pair of the queries, whether a context exists in which the extra term is not significant. 17. The method of claim 16 , where determining whether the context exists in which the extra term is not significant comprises: checking a data structure for an entry that associates the context with the extra term, the context including one or more terms with which the extra term appears in a query.