IDEM, EADEM, IDEM

DEMONSTRATIVE PRONOUN- "the same

                            SINGULAR

                   M        F        N

NOMINATIVE    idem        eadem        idem

GENITIVE          eiusdem    eiusdem    eiusdem

DATIVE              eidem         eidem         eidem

ACCUSATIVE   eundem       eandem      idem

ABLATIVE         eodem         eadem       eodem

                                    PLURAL

  NOMINATIVE    eidem         eaedem        eadem

GENITIVE           eorundem     earundem    eorundem

DATIVE                eisdem          eisdem          eisdem

ACCUSATIVE      eosdem          easdem        eadem

ABLATIVE            eisdem          eisdem          eisdem

NB: There is a definite similarity with is, ea, id- with the suffix -dem added. Note the change from m to n in accusative singular and genitive plural.

eidem pueri- the same boys

eandem puellam- the same girl