- An old term for sailing directions.
16th century. From Greek, same meaning.
Before maps were common, a periplus was used as a sort of atlas/handbook of sailing instructions, including the names of ports and commerce routes. The most famous one probably being the Periplus of the Erythraean Sea, published sometime during the first century AD, which detailed the modern-day Red Sea, Persian Gulf, Arabian Sea, and the Indian Ocean.
Rogers, J.G. (1985). Origins of Sea Terms. Mystic Seaport Museum.