Tolkien was criticized for using a plural [i.e. dwarves not dwarfs] that was not in the Oxford English Dictionary, which then (as now) is usually considered the final authority on such matters, particularly among those who count "correctness" as a virtue.
Much injured at this criticism, Professor Tolkien's response, in true professorial manner, was essentially,
"I wrote the dictionary."
He was, in fact, one of the editors.