imbecile
n. C2 Proficiency US //ˈɪmbəsaɪɫ// UK //ɪmbˈɛsaɪl// im·be·cile
n. a person who is very stupid or acts in a foolish way. It is a very rude word that people use to insult someone they think is not smart.
n. a person of low intelligence or a fool. Highly offensive and derogatory in modern usage; typically used as an insult to describe someone perceived as lacking common sense.
He called me an imbecile for making such a simple mistake.
The manager was an absolute imbecile and fired the entire team for a minor error.