Abstract: According to one embodiment, a first phrase having one or more keywords is received to be added to a phrase blacklist, where the first phrase has been determined to be related to unwanted content. An analysis is performed on the keywords of the first phrase to identifying a set of one or more related phrases that are related to the first phrase. The first phrase and the set of related phrases are added in the phrase blacklist. The phrase blacklist contains a plurality of phrases that have been determined to be related to unwanted content. The phrase blacklist is utilized to prevent a content item from appearing in a search result, in response to a search query having a phrase matching at least one of the phrases in the phrase backlist.