Pessulus

·noun A delicate bar of cartilage connecting the dorsal and ventral extremities of the first pair of bronchial cartilages in the syrinx of birds.

pessulus
pessŭlus, i, m. (neutr. collat. form in plur. pessula, Paul. Nol. Carm. 18, 412) [πάσσαλος], a bolt ...

A New Latin Dictionary by Charlton T. Lewis Ph.D. and Charles Short, LL. D.
pessulus
pessulus ī, m , πάσσαλος, a bolt: pessulum ostio obdo, bolt the door, T. ...

An Elementary Latin Dictionary