A MorphologicalProcessor tries to turn the inflected form of a word or phrase into
the form that can be found in WordNet. For example, if one calls
lookupBaseForm(POS.VERB, "running"), the index word for "run" should be returned.
Try to turn derivation into a word that is found in the index file for pos.
If there is more than one possible base form, then the first call to this method should
return the first base form found. The return value for subsequent calls is undefined (it could
be the same base form, or the next base form - it is up to the implementer to decide, but the
decision should be noted.