Definition of platitudinist in English:
platitudinist
noun ˌplatɪˈtjuːdɪnɪstˌplatɪˈtʃuːdɪnɪst
A person who utters or deals in platitudes; = platitudinarian.
Origin
Early 20th century; earliest use found in William Locke (1863–1930), novelist. From platitudin- + -ist.