1.  vanguard(n = noun.group) van - the leading units moving at the head of an army; Array
is a kind of army unit

2.  vanguard(n = noun.group) avant-garde, new wave, van - any creative group active in the innovation and application of new concepts and techniques in a given field (especially in the arts); Array
is a kind of art movement, artistic movement

3.  vanguard(n = noun.cognition) cutting edge, forefront - the position of greatest importance or advancement; the leading position in any movement or field; "the Cotswolds were once at the forefront of woollen manufacturing in England"; "the idea of motion was always to the forefront of his mind and central to his philosophy"
is a kind of perspective, position, view

   The troops who march in front of an army; the advance guard; the van. [1913 Webster]

vanguard, n.
1 the foremost part of an army or fleet advancing or ready to advance.
2 the leaders of a movement or of opinion etc.

Etymology:
earlier vandgard, (a)vantgard, f. OF avan(t)garde f. avant before (see AVAUNT) + garde GUARD

N  front, fore, forepart, foreground, face, disk, disc, frontage, facade, proscenium, facia, frontispiece, anteriority, obverse (of a medal or coin), fore rank, front rank, van, vanguard, advanced guard, outpost, first line, scout, brow, forehead, visage, physiognomy, phiz, countenance, mut, rostrum, beak, bow, stem, prow, prore, jib, pioneer, metoposcopy, fore, anterior, front, frontal, before, in front, in the van, in advance, ahead, right ahead, forehead, foremost, in the foreground, in the lee of, before one's face, before one's eyes, face to face, vis-a-vis, front a front, formosa muta commendatio est, frons est animi janua, Human face divine, imago animi vultus est indices oculi, sea of upturned faces.