This package contains different tools to add NLP capabilities for Lucene 4.x (it has been tested using Lucene version from 4.6.x to 4.8.1). Although it was originally developed for German, it is, mostly, language independent.
It allows the user to lemmatize words to be indexed, to weight termy ba their parts of speech (e.g. weighting nouns mor hevaily than pronouns), and to add synonyms taken from GermaNet or a list you provide to the search index and thereby increase recall of lucene.