The term for an animal that primarily eats grass is "herbivore." Herbivores are typically adapted to graze on grass, leaves, and other plant materials, which differ significantly from carnivores that consume meat. Examples of herbivorous animals include cows, sheep, horses, and rabbits. Their digestive systems are specially designed to break down plant cellulose, often using specialized stomach compartments or extended intestines to extract maximum nutrients from their diets. Herbivores play a significant role in ecosystems by aiding in plant population control and serving as a food source for predators, maintaining balance in the food web.