Parnahyba
a river of Brazil, rises in the Serra Mangabeiras, about lat. 9° S., and throughout its course (650 miles) forms the boundary between the states of Maranhão and Piauhy. It enters the Atlantic by six mouths. The stream is swift, but navigable by boats for nearly 350 miles. On the E. bank, 14 miles from its mouth, is the unhealthy town of Parnahyba, with a considerable trade.