The term 'stable staple' refers to a type of food that is commonly fed to horses and other livestock. OATS (4 letters), OAT (3 letters) and HAY (3 letters) are all examples of stable staples, as they are all nutritious and provide essential nutrients for animals. OATS are a type of cereal grain, while OAT and HAY are both types of grasses. All three of these stable staples are widely used in animal feed, providing a balanced diet for horses and other livestock.