Lewis Short
extempŏrālĭtas (noun F) : extemporalis
* The faculty of extemporaneous speaking or versifying, Suet. Tit. 3 (for which: extemporalis facultas,id. Aug. 84: facultas ex tempore dicendi,Quint. 10, 7, 1).
Charlton T. Lewis, Charles Short, A Latin Dictionary