The Collaborative International Dictionary of English v.0.48:

Diluvian \Di*lu"vi*an\, a. [Cf. F. diluvien.]
   Of or pertaining to a deluge, esp. to the Noachian deluge;
   diluvial; as, of diluvian origin. --Buckland.
   [1913 Webster]

WordNet (r) 3.0 (2006):

diluvian
    adj 1: of or connected with a deluge [syn: diluvian,
           diluvial]