Definition of mesopterygium in English:

mesopterygium

Pronunciation /mɪsɒptəˈrɪdʒɪəm/

noun

Ichthyology
  • 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.