Lewis Short
(adjective) : vānĭdĭcus, a, um, vanus-dico
* Vain - speaking; false - speaking; subst., a liar (ante- and post-class. and rare): cum probis potius quam cum improbis vivere vanidicis,Plaut. Trin. 2, 1, 37; Amm. 16, 7, 2.
Charlton T. Lewis, Charles Short, A Latin Dictionary