immutesco

A New Latin Dictionary by Charlton T. Lewis Ph.D. and Charles Short, LL. D.

immūtesco (inm-), tŭi, 3, v. inch. n. [in-mutesco],

to become dumb or speechless (post-Aug.): immutescamus alioqui, si nihil dicendum videatur, Quint. 10, 3, 16: ruptis ore querelis, Stat. Th. 5, 542.