island in the Gulf of St. Lawrence at the mouth of the St. Lawrence River, part of the Côte-Nord region, southeastern Quebec province, Canada. The island is 140 miles (225 km) long, and its greatest width is 35 miles (56 km). Anticosti rises to 625 feet (191 m) in hills along its north coast; it is well forested with spruce, fir, and pine. The island is a hazard to shipping.

The island was discovered by the French navigator Jacques Cartier in 1534 and named Assomption. Since the 17th century, it has been called Anticosti, a name probably derived from the Indian word naticosti, meaning “where bears are hunted.”

Granted to the French explorer Louis Jolliet in 1680, it was ceded by France to Great Britain in 1763 and was annexed to Newfoundland. It became part of Quebec province in 1774. After attempts to settle Anticosti failed, it was leased in 1895 by Henri Menier, a French chocolate manufacturer, who developed its resources. Menier's brother Gaston transferred ownership in 1926 to a Canadian paper corporation. Baie-Sainte-Claire was the first permanent settlement, but nearby Port-Menier, also called Baie-Ellis, is the island's only contemporary settlement and is a lumber port. Area 3,066 square miles (7,941 square km). Pop. (2006) 281.