Lewis & Short

antĕcursor, ōris, m. [antecurro], he that runs before; hence,

  1. I. In milit. lang.: antecursores, the forerunners of the army, the advanced guard, precursors, pioneers, Caes. B. G. 5, 47; id. B. C. 1, 16; 3, 36; so Vulg. Sap. 12, 8.
  2. II. In Tert. John the Baptist is so named, as the forerunner of Christ, Tert. adv. Marc. 4, 33.