A part of a horse's bridle that consists of a headstall with a noseband. When a martingale is used, it is attached to the horse's head at the cavesson.
From French caveçon, from Italian cavezzone, capezzone, augmentative of cavezza, probably from Latin caput (“head”), although derivation from Germanic has also been suggested; compare Old English cæfl (“bit, muzzle”).