mesopterygium
/mɪsɒptəˈrɪdʒɪəm/Ichthyol.
noun
In elasmobranch fishes: the central portion of the cartilaginous skeleton at the base of each pectoral fin.
Origin
Late 19th century; earliest use found in American Naturalist. From German Mesopterygium from meso- + ancient Greek πτερύγιον.