Meaning

• A runner at the front or ahead.

• By 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.

• A precursor or harbinger, a warning ahead.

• A forebear, an ancestor, a predecessor.

  "Bakelite is a forerunner of today's plastics."

• A postage stamp used in the time before a region or area issues stamps of its own.