The term 'Swamp Rodent' can be summarized by the 7-letter word 'Muskrat'. The muskrat is a semi-aquatic rodent native to North America and is found in wetlands, marshes, and swamps. It is a medium-sized mammal with a thick, brown fur coat and a long, scaly tail. It is an excellent swimmer and can stay underwater for up to 15 minutes. It feeds on aquatic plants, small fish, frogs, and crayfish.