In corpus linguistics, part-of-speech tagging (POS tagging or POST), also called grammatical tagging or word-category disambiguation, is the process of marking up a word in a text (corpus) as corresponding to a particular part of speech, based on both its definition and its context—i.e., its relationship with adjacent and related words in a phrase, sentence, or paragraph. A simplified form of this is commonly taught to school-age children, in the identification of words as nouns, verbs, adjectives, adverbs, etc. [Wikipedia]

Written in Python 3.

python postag-interactive.py

Sentence > Hello, part-of-speech tagger! NLP is an exciting field of applicable science!
Tagged : Hello/PRT ,/. part-of-speech/NOUN tagger/NOUN !/. NLP/NOUN is/VERB an/DET exciting/ADJ field/NOUN of/ADP applicable/ADJ science/NOUN !/.

There is still work to do. Currently I'm using only hidden markov model. Glad to collaborate on this and similar projects!

Regards,
Dahn.