1. An electronic dictionary comprising: (a) a dictionary memory having a multiplicity of data memory locations identified by respective addresses wherein: each of said data memory locations comprises a vocabulary memory location and a corresponding address memory location; said vocabulary memory locations store different vocabulary entries, said vocabulary entries including plural groups of related vocabulary entries and at least one of said related vocabulary entries of each of said groups constituting a corresponding at least one linking vocabulary entry for the corresponding group, each of said linking vocabulary entries being related to a corresponding other of said groups; and wherein, for each of said groups: each of said corresponding address memory locations for said related vocabulary entries not constituting said at least one linking vocabulary entry of the group stores data designating the address number of the vocabulary memory location at which is stored a predetermined different vocabulary entry of the group which is next to be retrieved; and the corresponding at least one address memory location for said at least one linking vocabulary entry of the group stores linking data for use in retrieving a predetermined vocabulary entry from said corresponding other of said groups; (b) input means for designating one of said different vocabulary entries; (c) search means responsive to said input means for locating the vocabulary memory location at which the vocabulary entry designated by said input means is stored; (d) retrieval means responsive to said search means for (i) first retrieving the data stored in the corresponding address memory location for said vocabulary memory location located by said search means; and (ii) second retrieving, if said first or subsequently retrieved data is address-number data, the vocabulary entry stored in the vocabulary memory location designated by the retrieved address-number data; and further retrieving the data stored in the corresponding address memory location for the retreived vocabulary entry; (e) group-linking means responsive to said retrieval means for linking, if said first or subsequently retrieved data is linking data, the currently retrieved group of vocabulary entries with a different group by (i) designating, based on the retrieved linking data, the address number of the vocabulary memory location for said predetermined vocabulary entry from said corresponding other of said groups which is associated with the retrieved linking data; and (ii) causing said retrieval means to retrieve said predetermined vocabulary entry from said corresponding other of said groups; and (f) display means for displaying each vocabulary entry retrieved by said retrieval means.
1. An electronic dictionary comprising: (a) a dictionary memory having a multiplicity of data memory locations identified by respective addresses wherein: each of said data memory locations comprises a vocabulary memory location and a corresponding address memory location; said vocabulary memory locations store different vocabulary entries, said vocabulary entries including plural groups of related vocabulary entries and at least one of said related vocabulary entries of each of said groups constituting a corresponding at least one linking vocabulary entry for the corresponding group, each of said linking vocabulary entries being related to a corresponding other of said groups; and wherein, for each of said groups: each of said corresponding address memory locations for said related vocabulary entries not constituting said at least one linking vocabulary entry of the group stores data designating the address number of the vocabulary memory location at which is stored a predetermined different vocabulary entry of the group which is next to be retrieved; and the corresponding at least one address memory location for said at least one linking vocabulary entry of the group stores linking data for use in retrieving a predetermined vocabulary entry from said corresponding other of said groups; (b) input means for designating one of said different vocabulary entries; (c) search means responsive to said input means for locating the vocabulary memory location at which the vocabulary entry designated by said input means is stored; (d) retrieval means responsive to said search means for (i) first retrieving the data stored in the corresponding address memory location for said vocabulary memory location located by said search means; and (ii) second retrieving, if said first or subsequently retrieved data is address-number data, the vocabulary entry stored in the vocabulary memory location designated by the retrieved address-number data; and further retrieving the data stored in the corresponding address memory location for the retreived vocabulary entry; (e) group-linking means responsive to said retrieval means for linking, if said first or subsequently retrieved data is linking data, the currently retrieved group of vocabulary entries with a different group by (i) designating, based on the retrieved linking data, the address number of the vocabulary memory location for said predetermined vocabulary entry from said corresponding other of said groups which is associated with the retrieved linking data; and (ii) causing said retrieval means to retrieve said predetermined vocabulary entry from said corresponding other of said groups; and (f) display means for displaying each vocabulary entry retrieved by said retrieval means. 2. An electronic dictionary as set forth in claim 1, wherein said dictionary memory comprises a basic-dictionary memory which stores at least one of said plural groups of vocabulary entries; and further comprises at least one expansion-dictionary memory which is optionally installed in the electronic dictionary and which stores at least one of said plural groups which is different from said at least one group stored in said basic-dictionary memory, said at least one linking vocabulary entry of said at least one group of vocabulary entries stored in said basic-dictionary memory being related to said at least one group stored in said at least one expansion-dictionary memory.