Lissencephaloid
An insult generally used to call another person stupid. Derives from the medical term for smooth-brainedness (lissencephaly). A harder-hitting form of the term "smooth-brain."
Adam: If pro is the opposite of con, what is the opposite of progress?
David: Dude, you're such a fucking lissencephaloid.
David: Dude, you're such a fucking lissencephaloid.