Found 2 items, similar to Mare clausum.
English → English (WordNet) Definition: mare clausum mare clausum n : (closed sea) a navigable body of water under the jurisdiction of a single nation
English → English (gcide) Definition: Mare clausum Mare clausum \Ma“re clau”sum\ [L.] (Internat. Law) Lit., closed sea; hence, a body of water within the separate jurisdiction of the nation; -- opposed to open sea (mare liberum ), the water open to all nations and over which no single nation has special control. [Webster 1913 Suppl.]