ˈ ̷ ̷ˌ ̷ ̷ noun
1.
a. : the posterior of the three primary divisions of the vertebrate brain or the parts developed from it including the cerebellum, pons, and medulla oblongata
b. : metencephalon 1 — distinguished from myelencephalon
c. : myelencephalon
2. : the posterior segment of the brain of an invertebrate (as an insect) : tritocerebrum