1. One who dissents; one who differs in opinion, or declares his disagreement.
2. One who separates from the service and worship of an established church; especially, one who disputes the authority or tenets of the Church of England; a nonconformist. Dissenters from the establishment of their several countries. (Burke) Robert brown is said to have the first formal dissenter. (Shipley)
The word is commonly applied only to protestants. The roman Catholics are generally referred to as a distinct class.