gyrencephala

from The Century Dictionary.

• In Owen's system (1857), one of four prime divisions of mammalians, containing the orders Cetacea, Sirenia, Hyracoidea, Proboscidea, Ungulata, Carnivora, and Quadrumana, having more or less numerous cerebral gyri, and the hemispheres of the cerebrum extending more or less over the cerebellum and olfactory lobes of the brain: distinguished from Archencephala, Lissencephala, and Lyencephala.

from the GNU version of the Collaborative International Dictionary of English.

• noun plural (Zoöl.) The higher orders of Mammalia, in which the cerebrum is convoluted.