Ambush

An ambush is a military tactic in warfare where one force uses concealment to attack a second force that moves into the area. Ambushers strike from concealed positions such as among dense underbrush, behind hilltops, and in camouflaged dugouts. This tactic is generally used by units below and up to platoon size, to attack units up to company size.

In civilian situations, it also means hiding where an intended victim is likely to come and committing some violence against him if he does. The legal term for it is "lying in wait," and in most criminal codes it is an aggravating factor, raising the seriousness of the crime and, therefore, increasing the penalty for it, because it proves premeditation.