1. a person who rides the leading left-hand horse of a team or pair drawing a coach or carriage, especially when there is no coachman.
Word Originmid 16th century (in the sense ‘forerunner acting as guide to the post-horse rider’): from French postillon, from Italian postiglione ‘post-boy’, from posta (see post2).
A postilion or postillion is a person who guides a horse-drawn coach or post chaise while mounted on the horse or one of a pair of horses. By contrast, a coachman controls the horses from the vehicle itself. Wikipedia
