Penn Treebank Tagset

Here are the most important tags. See also:
M. Marcus, Beatrice Santorini and M.A. Marcinkiewicz: Building a large annotated corpus of English: The Penn Treebank. In Computational Linguistics, volume 19, number 2, pp313-330.

POS Tag Description Example
CC coordinating conjunction and
CD cardinal number 1, third
DT determiner the
EX existential there there is
FW foreign word d'hoevre
IN preposition/subordinating conjunction in, of, like
JJ adjective green
JJR adjective, comparative greener
JJS adjective, superlative greenest
LS list marker 1)
MD modal could, will
NN noun, singular or mass table
NNS noun plural tables
NNP proper noun, singular John
NNPS proper noun, plural Vikings
PDT predeterminer both the boys
POS possessive ending friend's
PRP personal pronoun I, he, it
PRP$ possessive pronoun my, his
RB adverb however, usually, naturally, here, good
RBR adverb, comparative better
RBS adverb, superlative best
RP particle give up
TO to to go, to him
UH interjection uhhuhhuhh
VB verb, base form take
VBD verb, past tense took
VBG verb, gerund/present participle taking
VBN verb, past participle taken
VBP verb, sing. present, non-3d take
VBZ verb, 3rd person sing. present takes
WDT wh-determiner which
WP wh-pronoun who, what
WP$ possessive wh-pronoun whose
WRB wh-abverb where, when