1. A computer-implemented method comprising: selecting a hypernym from a hypernym repository; identifying a set of queries, from a query repository, that each include one or more terms that are hyponyms of the selected hypernym; determining a measure of specificity for the selected hypernym based at least on a comparison between (i) a probability distribution for co-occurrence of the one or more terms in the set of queries that are hyponyms of the selected hypernym, and (ii) a background probability distribution for the occurrence of the terms in the set of queries; determining whether the measure of specificity for the selected hypernym satisfies a threshold; and based on determining that the measure of specificity for the selected hypernym satisfies the threshold, determining whether to revise a subsequently received search query that includes one hyponym of the selected hypernym, to include another hyponym of the selected hypernym.