/ ˈvængɑːd; NAmE -gɑːrd/ noun (usually the vanguard ) [ sing. ]
1.
the leaders of a movement in society, for example in politics, art, industry, etc. :
The company is proud to be in the vanguard of scientific progress.
2.
the part of an army, etc. that is at the front when moving forward to attack the enemy
OPP rearguard
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WORD ORIGIN
late Middle English (denoting the foremost part of an army): shortening of Old French avan(t)garde , from avant before + garde guard.