North Korea's riposte to Donald Trump had many native English speakers reaching for their dictionaries.
A dispatch described the US president as "the mentally deranged US dotard".
Dotard means a person in a feeble and childish state due to old age.
It is a translation of "neukdari", a Korean word that refers to elderly people in a derogatory manner.
The Korean Central News Agency transmitted Kim Jong Un's statement verbatim.
It followed Mr Trump's speech at the UN this week mocking Mr Kim as a "Rocket Man" on a "suicide mission", and saying if the US is "forced to defend itself or its allies, we will have no choice but to totally destroy North Korea".
Past KCNA reports have used the Korean word "neukdari" against South Korean conservatives, but they rarely translate it as dotard.
Sometimes, it is translated into the neutral "old people" or omitted, depending on the context or the importance of the statement.
KCNA last used the word in 2012, when it called then South Korean president Lee Myung-bak "the traitor like a dotard."
The Korean version of Friday's dispatch uses "michigwangi", which means a mad or crazy person, before "neukdari", so a more accurate translation might have been a "crazy old man" or an "old lunatic".
In the past, KCNA has occasionally not published English versions of crude insults directed at US leaders or officials in an apparent effort to differentiate its statements for domestic audiences and outsiders.
KCNA called President Barack Obama a "monkey", in 2014, but attributed the remarks to a factory worker and did not issue an English version.
Later the same year, an unidentified North Korean defence commission spokesman called US secretary of state John Kerry a wolf with a "hideous lantern jaw", but again only in Korean.
After Mr Trump threatened North Korea with "fire and fury" in August, General Kim Rak Gyom, commander of the North's strategic rocket forces, was quoted in a KCNA Korean dispatch as saying Mr Trump showed his "senility" again.
But the KCNA English dispatch omitted that word.