Wiktionary
n. 1 An ocean surrounding a supercontinent. 2 (context less common English) Any ocean larger than the current Pacific Ocean.
Wikipedia
A superocean is an ocean that surrounds a supercontinent. It is less commonly defined as any ocean larger than the current Pacific Ocean. Named global superoceans include Mirovia, which surrounded the supercontinent Rodinia, and Panthalassa, which surrounded the supercontinent Pangaea. Pannotia and Columbia, along with landmasses before Columbia (such as Ur), were also surrounded by superoceans.
As surface water moves unobstructed east to west in superoceans, it tends to warm from the exposure to sunlight so that the western edge of the ocean is warmer than the eastern. Additionally, seasonal changes in temperature, which would have been significantly more rapid inland, probably caused powerful monsoons. In general, however, the mechanics of superoceans are not well understood.