Bridle is a word that originated from Germanic, and variations of the word that indicate its evolution, prior to being incorporated into modern English, include "bridel" (Middle English), "brigdels" (Old English) and "brittel" (Old High German).
A bridle most commonly refers to the accessory that is affixed to a horse's head for the purposes of navigation while riding. It resembles a mask, and has a bit that goes in the horse's mouth, which is attached to reins. The rider pulls the left or right rein, which pulls the horse's head in that direction, which typically propels the horse to walk or run in that direction as well. A bridle can also refer to anything that controls or represses something else. A bridle is also a term used in machinery to refer to a mechanism that restrains something else within a machine.
The action of bridling refers specifically to putting a bridle on a horse. It can also refer to the act of restraining something with something else.
"Bridle" can used to describe a person experiencing and demonstrating disgust or displeasure at something that bothers them, such as an offensive smell.