1. A method for search string expansion, the method comprising: receiving a list of reserved phrases, each reserved phrase in the list being related to a content and wherein each reserved phrase is associated with a portion of the content; categorizing each reserved phrase according to linguistic characteristics; generating a candidate list of synonyms for each reserved phrase in the list; filtering the candidate list of synonyms by: removing synonym duplicates; and comparing synonyms to a synonym rule and removing synonyms that do not comply with the synonym rule; categorizing each synonym in the filtered candidate list of synonyms according to linguistic characteristics of the associated reserved phrase; receiving a query string; identifying a matching synonym from the filtered list of candidate synonyms that matches a part of the query string; and determining if the part of the query string matches the linguistic characteristics of the matching synonym.