I read the following text in this link
JWNL Overview
Using JWNL is very simple. First, call JWNL.initialize() somewhere in the initialization code of your program.
Then, just call Dictionary.getInstance() to get the currently installed dictionary. The only dictionary methods you should really ever need to call are lookupIndexWord(), lookupAllIndexWords(), and getIndexWordIterator().
The other methods you may be interested in Relationship.findRelationships(), and those in PointerUtils.
Relationship.findRelationships() allows you to find relationships of a given type between two words (such as ancestry). Another way of thinking of a relationship is as a path from the source synset to the target synset.
The methods in PointerUtils allow you to find chains of pointers of a given type. For example, calling PointerUtils.getHypernymTree() on the synset that contains "dog," returns a tree with all its parent synsets ("canine"), and its parents' parents ("carnivore"), etc., all the way to the root synset ("entity").