Yes!
You can use the all_synsets function to loop over all the entries in wordnet...
>>> from nltk.corpus import wordnet as wn
>>> for synset in wn.all_synsets(): print synset
# (note, this will print out lots and lots of synsets)
Then if you grab one of those individual synset objects, you can get
its lemmas and get the part of speech out of that.
> --
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-- alexr