1. A computer-implemented method comprising: receiving a first search query; obtaining search results referencing a plurality of documents that a search engine has identified as being responsive to the first search query; computing a respective count of occurrences of each of a plurality of search queries for which a first document, of the plurality of documents, was identified as being responsive; designating, as entity text strings for the first document, one or more search queries having a respective count that satisfies a threshold; generating a refined search query having one or more terms from the one or more entity text strings for the first document, including combining (i) one or more terms of the one or more entity text strings for the first document with (ii) one or more terms of the first search query; and providing the refined search query having the one or more terms from the one or more entity text strings for the first document in response to receiving the first search query.