'Lying in wait' in the Bible

And when they had set the people, even all the host that was on the north of the city, and those lying in wait on the west of the city, Joshua went that night into the midst of the valley.

And it came to pass, when the king of Ai saw it, that they hasted, and rose up early, and the men of the city came out to meet Israel for battle, he and all his people, at an appointed time, before the waste plain, - he not knowing that there was an ambush lying in wait for him, behind the city.