The word "rein" is commonly used to refer to a strap or a piece of fabric that is used to control a horse. However, there are many synonyms for this word that can be used to add variety to one's writing. Some of the more commonly used synonyms for "rein" include "bridle," "harness," "halter," and "headstall." Each of these words has its own connotations and can be used in different contexts depending on the writer's intended meaning. Other synonyms for "rein" include "rope," "cord," "line," "tether," and "lead," all of which can provide interesting alternatives to the more standard use of the word "rein".