The Collaborative International Dictionary of English v.0.48:

Ambush \Am"bush\ ([a^]m"b[oo^]sh), v. t. [imp. & p. p.
   Ambushed ([a^]m"b[oo^]shd); p. pr. & vb. n. Ambushing.]
   [OE. enbussen, enbushen, OF. embushier, embuissier, F.
   emb[^u]cher, embusquer, fr. LL. imboscare; in + LL. boscus,
   buscus, a wood; akin to G. bush, E. bush. See Ambuscade,
   Bush.]
   1. To station in ambush with a view to surprise an enemy.
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            By ambushed men behind their temple laid,
            We have the king of Mexico betrayed.  --Dryden.
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   2. To attack by ambush; to waylay.
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