Lissencephala \Lis`sen*ceph"a*la\
(l[i^]s`s[e^]n*s[e^]f"[.a]*l[.a]), n. pl. [NL., fr. Gr.
lisso`s smooth + 'egke`falos the brain.] (Zool.)
A general name for all those placental mammals that have a
brain with few or no cerebral convolutions, as Rodentia,
Insectivora, etc.
[1913 Webster] Lissom