Entry 1 sense Webster, 1913 Diluvian · Di·lu·vi·an · IPA /daɪˈluvɪən/ 01 a. Of or pertaining to a deluge, esp. to the Noachian deluge; diluvial; as, of diluvian origin. 1. Of or pertaining to a deluge, esp. to the Noachian deluge; diluvial; as, of diluvian origin.