1. (noun)Bismarck Sea an arm of the South Pacific to the southwest of the Bismarck Archipelago Synonyms: battle of the Bismarck Sea
2. (noun)Bismarck Sea, battle of the Bismarck Sea a naval battle in World War II; Allied land-based bombers destroyed a Japanese convoy in the Bismarck Sea in March 1943 Synonyms: battle of the Bismarck Sea