Lewis Short
(adjective) : convertĭbĭlis (convers-), e, id.
* Changeable (post-class.): propositiones,App. Dogm. Plat. 3, p. 33, 1 and 2 (al. conversibilis): deus convertibilis et demutabilis,Prud. Apoth. 344.—Hence, con-vertĭbĭlĭter, adv., changeably (late Lat.), Aug. Music. 5, 13.
Charlton T. Lewis, Charles Short, A Latin Dictionary