n-gram

In the fields of computational linguistics and probability, an n-gram is a contiguous sequence of n items from a given sequence of text or speech. Google Ngram viewer (link) -developed by Jon Orwant and Will Brockman and released in December 2010- is an  online search engine that charts frequencies of any set of comma-delimited search strings using a yearly count of n-grams found in sources printed between 1500 and 2008. 

Ngram chart of my first name (Bilal) 😉

Ngram chart of Molecular Dynamics (peaked in 1995)

Ngram chart of QSAR (peaked in 1997)