Kim Jong-un’s latest broadside against Donald Trump had people across the globe reaching for a dictionary as he described the President as a “mentally deranged US dotard” in his latest outburst yesterday.

The antiquated expression is defined as “an old person, especially one who has become weak or senile”.

Merriam and Webster says in modern usage it commonly means “a person in his or her dotage”. It comes from the Middle English word doten (meaning "to dote"), which initially had the meaning of "imbecile" when it began being used in the 14th century.