うすばか

noun, na-adjective

dimwit; simpleton; fool

A mildly derogatory term for a foolish or slow-witted person; not extremely harsh but clearly insulting.

• あいつは本ほん当とうにうすばかだな。

  That guy is a real dimwit.

• うすばかなことを言いうな。

  Don't say such stupid things.