. . . . . . . . "NCI: Any one of several species in the genus Rattus.,NCI: The common rat, Rattus norvegicus, often used as an experimental organism." . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .