postilion

noun

Etymology: From Middle French postillon, and its likely source, Italian postiglione (“guide for driver of post-coach”), from posta (“post”).

1. A rider mounted on the near (left) leading horse who guides the team pulling a carriage.

   “C’est un garcon de bonne fortune, said the landlord, pointing through the window to half a dozen wenches who had got round about La Fleur, and were most kindly taking their leave of him, as the postilion was leading out the horses.”

   “The postilion seized one of his fat horses by the tail, and swung himself up to his seat again.”

2. A post-boy, a messenger boy, a swift letter carrier.