1) An escort who rides ahead 2) Attendant on horseback 3) Bodyguard 4) Escort 5) Escort for a vehicle 6) Forerunner 7) Vanguard member 1) Precursor 2) Scout 
• (n.) One who rides out on horseback. • (n.) A servant on horseback attending a carriage. • (n.) A summoner whose office is to cite men before the sheriff.
Out'rid`er noun 1. A summoner whose office is to cite men before the sheriff. [ Obsolete] 2. One who rides out on horseback. [ Obsolete] Chaucer. 3. A servant on horseback attending a carriage. 
[n] - an escort who rides ahead (as a member of the vanguard)
noun an escort who rides ahead (as a member of the vanguard)
a mounted attendant riding before or beside a carriage. · (at a racetrack) a mounted rider who accompanies or leads a racehorse to the post. · a person who goes in advance of an automobile or person to clear a passage. · a person who leads the way or is a member of a vanguard; forerunner. · a person who rides out or forth, es...