'Hydromancy' definitions:

Definition of 'hydromancy'

(from WordNet)
noun
Divination by water (as by patterns seen in the ebb and flow of the tides)

Definition of 'Hydromancy'

From: GCIDE
  • Hydromancy \Hy"dro*man`cy\, n. [Hydro-, 1 + -mancy: cf. F. hydromancie.] Divination by means of water, -- practiced by the ancients. [1913 Webster]