Insulting Word for a Fool or an Idiot

Puzzle 4 of Hellos and Goodbyes Easy Pack

Question is: Insulting Word for a Fool or an Idiot

and the answer is: IMBECILE

Word Meaning:

IMBECILE — (obsolete) A person with limited mental capacity who can perform tasks and think only like a young child, in medical circles meaning a person who lacks the capacity to develop beyond the mental age of a normal five- to seven-year-old child.

Definitions from Wiktionary.