The word 'ambush' is a noun which can mean

(1) the act of lying in wait to attack someone by surprise.

(2) an attack made in this way.

(3) the person or people making such an attack.

(4) the place of concealment from which the attack is made.

It is also a verb meaning to lie in wait for someone or attack them in this way.

It entered the language around the 14th century and comes from the French word 'embuschier' meaning 'to place men in the woods'.

More Info: www.chambers.co.uk