1. A computer-implemented method of filtering search results returned for a search query, wherein the search results include one or more documents, the method comprising: identifying at least a first search term included in the search query; determining, by operation of one or more computer processors, a plurality of word usage senses associated with the first search term; selecting a first word usage sense from the plurality of word usage senses associated with the first search term for use in filtering the search results; filtering the search results to include only documents in which the first search term is used in a word usage sense matching the selected first word usage sense, wherein at least one document in which the first search term is used in a different word usage sense is filtered out of the search results; and returning the set of filtered search results as the search results for the search query.