Chuuk (chŏk) [key] or Truk trŏk, trŭk, state (1990 est. pop. 48,853), c.39 sq mi (100 sq km), Federated States of Micronesia, W Pacific, in the E Caroline Islands. One of four states comprising the Federated States of Micronesia, Chuuk consists of c.55 volcanic islands surrounded by an atoll reef and many islets. The chief products are copra and dried fish. During World War II, Chuuk was the site of an important Japanese naval base.