The term 'Horned Grazer' refers to two large mammals, the rhinoceros (5 letters) and the GNU (3 letters). Both animals are herbivores that feed on grasses and other vegetation. The rhinoceros is characterized by its thick skin and one or two horns on its snout, while the GNU has a long, curved horn on its forehead. Both animals are found in Africa and Asia, and are considered to be endangered species due to poaching and habitat loss.