a small animal that carries its young in a pouch or on its back. The opossum is a mammal, feeds at night and lives mostly in trees. There are several kinds, making up a family (group of related animals or plants) of animals. One kind, when caught or frightened, pretends to be dead. The opossum is common in the United States, Canada and South America. —Notes on the Lectures Glossary Final approval 26 March 1990