1. A system for identifying documents matching a document metaprint, comprising: a processor to execute modules of the system stored in a memory of a computer-readable storage medium, the modules comprising: a metadata index module for creating a metaprint for each document in a corpus of documents, comprising: an extraction module for extracting metadata keywords from the document; a calculator module for calculating a word frequency of occurrence of each of the metadata keywords extracted from the document; a word frequency module for generating a metaprint forward index for the document comprising a list of metadata of the document and the calculated word frequency of each of the metadata keywords of the document; a merge module for resorting and merging the metaprint forward indexes across all of the documents in the corpus into a metadata search index comprising: a word frequency storage module for storing the word frequency for each of the metadata keywords into the metadata search index; a supplement module for supplementing each metadata keyword with one or more synonyms of the metadata keyword; and a synonym storage module for storing the synonyms into the metadata search index keyed on the metadata keyword and generating the metaprint for the document; a search index module for generating a search index comprising one or more words that are not the metadata keywords extracted from those documents in the corpus; a metadata keyword module for receiving a search query comprising one or more search terms from a user; an application module for applying the search query to the metadata search index; an identification module for identifying one or more of the metadata keywords matching the one or more of the search terms; a metaprint query module for retrieving the metaprint associated with each of the matched metadata keywords and for generating a metaprint search query from the retrieved metaprints associated with each of the matched metadata keywords and the synonyms for each of the matched metadata keywords; a metaprint query execution module for applying the metaprint search query to the search index and identifying documents that contain similar word frequencies or metaprints with the metaprint search query; and a metaprint query results module for obtaining search results comprising documents matching the metaprint search query.