outrider

noun

1. a mounted attendant riding before or beside a carriage.
2. (at a racetrack) a mounted rider who accompanies or leads a racehorse to the post.
3. a person who goes in advance of an automobile or person to clear a passage.
4. a person who leads the way or is a member of a vanguard; forerunner.
5. a person who rides out or forth, especially a scout, cowhand, ranch hand, or the like.

noun

1. a person who goes ahead of a car, group of people, etc, to ensure a clear passage
2. a person who goes in advance to investigate, discover a way, etc; scout
3. a person who rides in front of or beside a carriage, esp as an attendant or guard
4. US a mounted herdsman

n.mid-14c., from out (adv.) + rider.