Definition of diencephalon in English English dictionary
The region of the human brain, specifically the human forebrain, that includes the thalamus, the hypothalamus, the epithalamus, the prethalamus or subthalamus, and the pretectum
{i} middle brain, section of the brain between the mesencephalon and prosencephalon (Anatomy)
The diencephalon is the portion of the embryonic brain that develops into the thalamus, hypothalamus, and associated structures, all of which make up the diencephalon (hindbrain) in the adult It includes structures important in the visual pathway Some sources consider the adult diencephalon to be part of the brainstem
Greek dia = between, and enkephalos = brain, hence in general the structures surrounding the 3rd ventricle adjective - diencephalic