What is a "nag"?

A nag is a term used to describe a horse that is old or worn out, or one that is considered of little value. Typically, a nag is a small or thin horse that has become weak or feeble due to age or overuse. These horses may have a bad temperament and be difficult to work with, making them less desirable for riding or work. The term "nag" is often used to refer to a horse that is in poor condition or one that is no longer useful for its intended purpose. However, it is important to note that this term can be considered derogatory by some horse owners and enthusiasts, as it implies a lack of respect or value for the animal.