A corpus of texts relating to a domain of knowledge may be searched by determining word-pair proximity scores measuring associations between pairs of words that appear in the corpus and that are semantically related to the domain of knowledge. When a search term is received, the word-pair proximity scores may be used (at least in part) with dictionary overlays, user feedback, and other feature vectors as weighting mechanisms to identify one or more related words that are strongly associated with the search term within the corpus. One or more texts may be selected from the corpus, texts in which the search term and the related words appear near each other in one or more places. The selected texts may be categorized and/or clustered based on the related words before being returned for presentation as Search Results.