A method of filtering content from a data set includes accepting a search request directed to a data set associated with a site, the search request including a search term that is not among terms represented in a site-specific lookup table representing site-specific relatedness of terms in that data set, such related terms including any of synonyms, hypernyms and hyponyms; generating an approximating lookup table by applying a transformation function to a corpus lookup table, the corpus lookup table representing relatedness, in a general corpus, of terms in the data set; identifying terms represented in the approximating lookup table that are related terms of the search term; and filtering from the data set digital content that includes any of the search term and the terms identified from the approximating table as related terms of the search term.