/pel"i keuh sawr'/ , n.
any of a group of large primitive reptiles belonging to the extinct order Pelycosauria, abundant in North America and Europe during the Permian Period, often having a tall spinal sail.
[ Pelycosauria (1878), equiv. to Gk pelyk-, s. of pélyx wooden bowl, cup (taken as meaning PELVIS, parallel to the NL sense of L pelvis ) + -o- -O- + saûr ( os ) -SAUR + NL -ia -IA; so named from the peculiar form of the ischium in such reptiles ]