title: POS tagging base form of noun
body: <p>I would like to search a sentence based on the presence of a noun of any form. Processing becomes an issue when Im looking through very large texts and searching for all the different permutations of POS tags for a noun- namely NN,NNS,NNPS,NNS (and probably others). My question is therefore whether NN is the base form of all the other noun variants and whether I can just search for NN. The same applies to adverbs, pronouns and verbs. Do POS tags have base forms?</p>