Lewis Short
immūtātĭo | inm- (noun F) : (), , immuto
* A change, exchanging, interchange, substitution of one thing for another in speech: verborum,Cic. Ac. 2, 6, 16: ordinis,id. de Or. 3, 44, 176: si verborum immutationibus utantur, quos appellant τρόπους, id. Brut. 17, 69.
* Esp., rhet. t. t., metonymy, the indirect naming of any thing = ἀλλοιωσις, μετωνυμία: immutationes nusquam crebriores,i. e. metonymies,id. Or. 27, 94; id. de Or. 3, 54, 207; cf. Quint. 9, 1, 35: faciebat barbarismos immutatione, cum c pro g uteretur, id. 1, 5, 12; cf. ib. 6.
Charlton T. Lewis, Charles Short, A Latin Dictionary