Bayard (bā'urd) [key], Ital. Baiardo (bäyär'dō) [key], in chivalric romance, a bay horse, remarkable for his spirit and for his unique ability to fit his size to his rider. He appears in the 12th-century French epic Renaud de Montauban and in later tales of Roland by Boiardo, Ariosto, and Tasso.