1. A computer-readable storage medium encoded with a dictionary data structure, the data structure 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.