1. A text index, comprising a data structure stored in a memory for access by at least one application program being executed on a data processing system, for use in the preparation of semantically associated text searches of electronic documents in a search engine, said text index comprising: one or more content records corresponding to an electronic document, the content records identifying one or more text terms present within the electronic document; one or more term association records associating a text term present within the electronic document identified by a content record with a pre-determined semantic definition of the text term; one or more content association records linking a term association record of the one or more term association records with a content record of the one or more content records; wherein a user is enabled to provide one or more user-defined text search terms desired to be located within the text index; wherein, for user-defined text search terms having term association records within the search index, the user is iteratively presented a list of one or more pre-determined semantic definitions associated with each of the one or more user-defined text search terms, enabling the user to select a pre-determined semantic definition of those one or more user-defined text search terms; wherein the one or more content association records contained within the text index are searched using the user-defined text search terms to locate electronic documents previously catalogued as containing the one or more user-defined text search terms in association with the selected pre-determined semantic definitions, to form a semantically relevant results set; wherein new term association records are updated or created during the use of the text index by enabling a user to select pre-determined semantic definitions for association with user-defined text search terms; and wherein new content association records are updated or created during the use of the text index in a search, by associating a particular electronic document with the use-defined text search terms, and selected pre-determined semantic definitions of the user-defined text search terms, used to locate the particular electronic document.