from nltk.corpus import wordnet as wn
res=wn.synset('locomotive.n.01').lemma_names()
print res

[u'locomotive', u'engine', u'locomotive_engine', u'railway_locomotive']

from nltk.corpus import wordnet as wn
resdef = wn.synset('ocean.n.01').definition()
print resdef

a large body of water constituting a principal part of the hydrosphere

from nltk.corpus import wordnet as wn
res_exm = wn.synset('good.n.01').examples()
print res_exm

['for your own good', "what's the good of worrying?"]

from nltk.corpus import wordnet as wn
# get all the antonyms
res_a = wn.lemma('horizontal.a.01.horizontal').antonyms()
print res_a

[Lemma('inclined.a.02.inclined'), Lemma('vertical.a.01.vertical')]