1. A method comprising: generating a query conceptual graph for a search query, the query conceptual graph comprising: a plurality of graph terms, a graph term representing a concept type; a plurality of conceptual relation nodes that each comprise text describing a relationship between two or more of the plurality of graph terms; and a plurality of arcs that each indicate a direction of the relationship described by the text of a corresponding conceptual relation node of the plurality of conceptual relation nodes; identifying at least one set of conceptually similar terms for at least one graph term of the query conceptual graph, the at least one set of conceptually similar terms mapped to the corresponding concept type represented by the respective at least one graph term; searching a plurality of documents in accordance with a search query based at least in part on the query conceptual graph and on the set of conceptually similar terms; selecting a document from the plurality of documents as a potential match to the search query if, when the query conceptual graph is compared to a document conceptual graph for the document, there is at least one corresponding term associated with the query conceptual graph that matches at least one corresponding term associated with the document conceptual graph, wherein the corresponding term associated with each respective conceptual graph comprises at least one or more of: terms representing a concept type, and terms that are conceptually similar to the terms representing concept types; accessing one or more onomasticons, each onomasticon comprising a list of one or more mappings, each mapping comprising a mapping of a predetermined concept type to a corresponding set of conceptually similar terms; and validating that the potential match is a valid match if a set of conceptually similar terms of the query conceptual graph, and a set of conceptually similar terms of the document conceptual graph that is associated with the potentially matching document, map to the same concept type in one or more onomasticons.