Lewis Short
purpŭrissum | purpŭrissus (noun N) : (
* Masc. collat. form , Hier. Ep. 54, 7), = πορφυρίζον, a kind of dark purple color, used for dyeing red and as a cosmetic, Plin. 35, 6, 12, § 30; Plaut. Most. 1, 3, 104; Naev. and Afran. ap. Non. 218, 30 and 31; Hier. Ep. 127, 3.
* Transf.: quid in oratione meā purpurisso litum,highly colored,Front. Or. 2, p. 248.
Charlton T. Lewis, Charles Short, A Latin Dictionary