A system (100) for searching and retrieving documents includes a database (106), a memory device (108), a user interface device (102) and a controller (104). The database (106) stores documents. The memory device (108) stores software, tokens and an index. The software performs methods according to a background routine (118) and a foreground routine (116). Each token (e.g., speed) has related expressions (e.g., miles per hour, mph, kilometers per hour, and kph) assigned thereto that define the token. The index has documents, having an occurrence of one of the related expressions for one of the tokens, assigned to the one of the tokens. The user interface device (102) accepts and sends search queries having a token and receives information related to the documents, having an occurrence of the related expressions for the token, responsive to a user interface process (120). The controller (104) is electrically coupled to the memory device (108), the user interface device (102) and the database (106). The controller (104) manages communications between the memory device (108) and the user interface device (102) responsive to the foreground routine (116) in the software to respond to the search queries having the token. The controller (104) also manages communications between the memory device (108) and the database (106) responsive to the background routine (118) in the software to create the index.