1. A computer-readable storage medium that is not a signal, the computer-readable storage medium for storing data for access by a program being executed on a data processing system, comprising: a dictionary data structure stored in the computer-readable storage medium, the dictionary data structure including information used by the program and comprising: a first table comprised of entries each representing a natural language term, each entry of the first table containing a term ID identifying its term; a second table comprised of entries each representing a definition, each entry of the second table containing a definition ID identifying its definition; and a third table comprised of entries each representing correspondence between a term and a definition defining the term, each entry of the third table containing a term ID identifying the defined term and a definition ID identifying the defining definition, such that the contents of the data structure are usable to identify any definitions corresponding to a term.