1) Body of water 2) Water 1) Marine 
marine; of seas; of inland seas
• (a.) Of or pertaining to the sea; -- sometimes applied to rocks formed from sediments deposited upon the sea bottom.
Tha·las'sic adjective [ Greek ... the sea.] (Geol.) Of or pertaining to the sea; -- sometimes applied to rocks formed from sediments deposited upon the sea bottom. 
In geology, thalassic describes rocks pertaining to the sea. The term is sometimes applied to rocks formed from sediments deposited upon the sea bottom.
[adj] - relating to the seas, especially smaller or inland seas
thalassic 1. A reference to the sea or ocean; sometimes thalassic is distinguished from oceanic, as applying to seas, gulfs, etc., rather than to oceans. 2. Relating to inland seas or minor seas such as the Aegean or to the deposition of fine-grained sediments in relatively deep, still water.
adjective relating to the seas, especially smaller or inland seas; `deposits of sediment in gulfs and seas rather than in the ocean proper are known as thalassic deposits`- Scientific American