Disambiguating Keywords And Other Query Terms Used To Select Sponsored Content

A disambiguation process is applied to query terms before they are used to select sponsored content. If a query term is identified as ambiguous it is replaced by phrases associated with the ambiguous term. The disambiguation process provides, as an output, these phrases for use in selecting sponsored content. One example method for identifying ambiguous query terms includes, for each of a plurality of unigrams, identifying phrases containing the unigram, measuring similarity between phrases for each pair of phrases containing the unigram and using the measured similarity to mark at least some of the plurality of unigrams as ambiguous.