insessor, ōris, m. [insideo],
a besetter , occupant (very rare); of a ship, Jul. Val. Res Gest. Alex. 1, 1: viarum, a waylayer , Symm. Ep. 2, 48; cf.: insessores, latrones, Paul. ex Fest. p. 111 Müll.: quod circa vias insidientur sedentes.
·noun One of the Insessores. The group includes most of the common singing birds. ...
Webster's Dictionary of the English Language