A similarity analysis framework is described herein which leverages two or more similarity analysis functions to generate synonyms for an entity reference string re. The functions are selected such that the synonyms that are generated by the framework satisfy a core set of synonym-related properties. The functions operate by leveraging query log data. One similarity analysis function takes into consideration the strength of similarity between a particular candidate string se and an entity reference string re even in the presence of sparse query log data, while another function takes into account the classes of se and re. The framework also provides indexing mechanisms that expedite its computations. The framework also provides a reduction module for converting long entity reference strings into shorter strings, where each shorter string (if found) contains a subset of the terms in its longer counterpart.