van·guard /ˈvænˌgɑrd ||ˈvæŋ-/
  前鋒,先鋒,先驅
  Van·guard n.  Mil. The troops who march in front of an army; the advance guard; the van.
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  vanguard
       n 1: the leading units moving at the head of an army [syn: van]
       2: any creative group active in the innovation and application
          of new concepts and techniques in a given field
          (especially in the arts) [syn: avant-garde, van, new
          wave]
       3: the position of greatest advancement; the leading position
          in any movement or field [syn: forefront, cutting edge]