Although the substantive platitude is in common use, one almost never hears or reads its derived adjective platitudinous ‘characterized by platitudes; full of platitudes; (of a person) that utters or writes platitudes’ (Oxford English Dictionary Online). The latter is a very useful item to have in one’s active vocabulary, since so much of what passes for meaningful in modern life and thought is at bottom banal, flat, and patently platitudinous.