dimwitted

This term carries a strong negative connotation and is generally considered insulting. It describes a lack of mental agility or a failure to grasp simple concepts, often implying a permanent state of slowness rather than a temporary lapse in judgment.

In terms of register, it is more informal than "unintelligent" or "obtuse" but less vulgar than certain slang terms for stupidity. It is frequently used in storytelling or descriptive prose to characterize a person as naive or easily fooled, often evoking a sense of frustration or pity in the speaker.