Definition of "diencephalon"
diencephalon
/ˌdaɪənˈsɛfəlɒn/
noun
plural diencephalons or diencephala
(neuroanatomy, anatomy) 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.