I think it's easier to read the index.noun file directly. Have a lot at http://wordnet.princeton.edu/man/wndb.5WN for the format of that file (it's an easy to parse, line-oriented text file.)

Example content of the index.noun file:

...
ablution n 1 2 @ + 1 0 00251698
abm n 1 1 @ 1 0 02691561
abnaki n 2 1 @ 2 0 09507567 06815704
abnegation n 2 2 @ + 2 0 07105993 00202053
abnegator n 1 2 @ + 1 0 09611669
abney_level n 1 1 @ 1 0 02643435
abnormal_condition n 1 2 @ ~ 1 0 14309161
abnormal_psychology n 1 1 @ 1 0 06057161
abnormalcy n 1 2 @ ~ 1 0 14309161
...
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