To minimise the risk of including random concatenations of words, rare spellings or mistakes, any word or expression had to appear in the corpus at least 40 times to merit inclusion in the final, chronologically ordered set.

ECONOMIST: Science invades the humanities

Over time, the meaning of a word or an expression drifts.

CNN: LOL isn't funny anymore

According to the Oxford English Dictionary, the word has now come to mean an expression of excited approval.

BBC: Supercalifragilisticexpialidocious: What does it mean?

Its mime-trained members have reintroduced physical expression into a theatre which had become word-bound, and developed an intense style far from traditional naturalism.

ECONOMIST: Repertory theatre in Britain

Nevertheless, one close ally of the prime minister told me that his colleague should not be put through the mill for a "momentary expression of exasperation" and said that he would be very surprised if the "pleb" word would have been used.

BBC: Andrew Mitchell: It doesn't look good