outrider(n = noun.person) - an escort who rides ahead (as a member of the vanguard);
is a kind of bodyguard, escort

1.  A summoner whose office is to cite men before the sheriff. [1913 Webster]

2.  One who rides out on horseback, beyond the main group, e. g., as a scout. Chaucer. [1913 Webster]

3.  A servant on horseback attending a carriage. [1913 Webster]

outrider, n.
1 a mounted attendant riding ahead of, or with, a carriage etc.
2 a motor cyclist acting as a guard in a similar manner.
3 US a herdsman keeping cattle within bounds.

Derivative:
outriding n.

N  precursor, antecedent, precedent, predecessor, forerunner, vancourier, avant-coureur, pioneer, prodrome, prodromos, prodromus, outrider, leader, bellwether, herald, harbinger, foreboding, dawn, avant-courier, avant-garde, bellmare, forelooper, foreloper, stalking-horse, voorlooper, voortrekker, prelude, preamble, preface, prologue, foreword, avant-propos, protasis, proemium, prolusion, proem, prolepsis, prolegomena, prefix, introduction, heading, frontispiece, groundwork, preparation, overture, exordium, symphony, premises, prefigurement, omen, precursory, prelusive, prelusory, preludious, proemial, introductory, prefatory, prodromous, inaugural, preliminary, precedent, a precedent embalms a principle.