a. 1. Inclined to wild sports; delighting in rash, absurd, or dangerous amusements. “The merry madcap lord.” Shak. [ 1913 Webster ]
2. Wild; reckless. “Madcap follies” Beau. & Fl. [ 1913 Webster ]
n. A person of wild behavior; an excitable, rash, violent person. Shak. [ 1913 Webster ]