The anterior of the three principal divisions of the brain, including the prosencephalon and thalamencephalon. Sometimes restricted to the prosencephalon only. See Brain.
- The most anterior of the three primary regions of the embryonic brain from which the telencephalon and diencephalon develop.
- The segment of the adult brain that develops from the embryonic forebrain and includes the cerebrum, thalamus, and hypothalamus.