diencephalon UK /ˌdaɪ̯.ənˈsɛfəlɒn/US /ˌdaɪ̯.ənˈsɛfəlɑn/ noun1 •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. formsdiencephala · diencephalons
