What is a dotard? Kim Jong-un's archaic insult towards Donald Trump explained

Kim Jong-un's latest attack in an escalating war of words with Donald Trump sent people across the world to their dictionaries.

The North Korean leader branded the President a "mentally deranged US dotard" in a scathing speech delivered personally through state media.

Pyongyang is notorious for the bombastic, derogatory and often awkward English phrases it uses to lash out at enemies.

But Kim's use of "dotard" left many people scratching their heads.

The Oxford English Dictionary defines the word as "an old person, especially one who has become weak and senile".

Merriam-Webster gives "a person in his or her dotage," with dotage defined as "a state or period of senile decay marked by decline of mental poise and alertness".

The publisher said the word derived from the Middle English "doten" - meaning to dote - and originally meant "imbecile" when first used in the 14th century.

It added searches for the term were "sky high" on its website following Kim's speech, which was issued verbatim by Korean Central News Agency.