rhombencephalonPronunciation: /ˌrɒmbɛnˈsɛf(ə)lɒn, -ˈkɛf-/Definition of rhombencephalon noun Anatomy another term for hindbrain.Origin: late 19th century: from rhomb + encephalonrhombencephalon in other Oxford dictionaries Definition of rhombencephalon in the US English dictionary