pessulus
/ˈpɛsjʊləs/Zoology
noun
In some birds: a cartilaginous or bony bar at the junction of the bronchi, forming part of the syrinx.
Origin
Early 19th century (in an earlier sense). From classical Latin pessulus a bolt from ancient Greek πάσσαλος (Attic πάτταλος): see passalid noun.