the foremost division or the front part of an army; advance guard; van.
2.
the forefront in any movement, field, activity, or the like.
3.
the leaders of any intellectual or political movement.
4.
( initial capital letter ) Rocketry.a U.S. three-stage, satellite-launching rocket, the first two stages powered by liquid-propellant engines and the third by a solid-propellant engine.
Origin: 1480–90; earlier van(d)gard(e) < Middle Frenchavangarde, variant of avant-garde; see avaunt, guard