Definitionen
1.NounA runner at the front or ahead.
2.NounBy extension, a non-competitor who leads out the competitors on to the circuit, or who runs/rides the course prior to competitor trials, usually testing or checking the way.
3.NounA precursor or harbinger, a warning ahead.
4.NounA forebear, an ancestor, a predecessor."Bakelite is a forerunner of today's plastics."
5.NounA postage stamp used in the time before a region or area issues stamps of its own.