How to recognize a two part term when the space is removed? ("bigdata" and "big data") I'm not a NLP guy and I have this question. 

I have a text dataset containing terms which go like, "big data" and "bigdata". 

For my purpose both of them are the same. 

How can I detect them in NLTK (Python)?

Or any other NLP module in Python?
There is a nice implementation of this in gensim: http://radimrehurek.com/gensim/models/phrases.html

Basically, it uses a data-driven approach to detect phrases, ie. common collocations. So if you feed the Phrase class a bunch of sentences, and the phrase "big data" comes up a lot, then the class will learn to combine "big data" into a single token "big_data". There is a more complete tutorial-style blog post about it here: http://www.markhneedham.com/blog/2015/02/12/pythongensim-creating-bigrams-over-how-i-met-your-mother-transcripts/