Oxford English Dictionary

The Oxford English Dictionary was an English language dictionary, which was around by the 21st century.

The Fifth Doctor admitted that, while the term "psychologico-human" was first coined by Professor Dorkus Merriman in the late 21st century, the word was not, in fact, included in the Oxford English Dictionary until 2107. (PROSE: Observation)

Behind the scenes
As of 2020, the Oxford English Dictionary includes the word Dalek in it, where it describes it as - "a member of a race of hostile alien machine-organisms which appeared in the BBC science-fiction serial Dr Who from 1963. [invented word, named after an encyclopedia volume covering the alphabetical sequence da-lek].