Lewis Short
(adjective) = ἄκαυστος: ăcaustus, a, um
* Incombustible; hence subst. m. (sc. lapis), the carbuncle, since it was regarded as incombustible: acaustoe (i. e. ἄκαυστοι), Plin. 37, 7, 25, § 92; v. Sill. a. h. l.
Charlton T. Lewis, Charles Short, A Latin Dictionary