noun / verb
(noun) headgear used to control a horse
(verb) to put a bridle on a horse; to restrain or control; to show resentment or anger
Think of a horse's **bridle** which is used to **control** it. To **bridle** an emotion means to **control** or **restrain** it. If someone **bridles** at a comment, they are showing anger, like a horse resisting the bridle.