What is Ambush?

Legal Definition
An ambush is a long-established military tactic in which combatants take advantage of concealment and the element of surprise to attack unsuspecting enemy combatants from concealed positions, such as among dense underbrush or behind hilltops. Ambushes have been used consistently throughout history, from ancient to modern warfare. In the 20th century, an ambush might involve thousands of soldiers on a large scale, such as over a choke point such as a mountain pass, or a small guerrilla band or insurgent group attacking a regular armed force patrol.
-- Wikipedia
Legal Definition
The noun "ambush" means

(1) the act of attacking an enemy unexpectedly from a concealed station;

(2) a concealed station, where troops or enemies lie in wait to attack by surprise, an ambuscade;

(3) troops posted in a concealed place for attacking by surprise. The verb "ambush" means to lie' in wait, to surprise, to place in ambush. Dale County v. Gunter, 46 Ala. 142.
-- Black's Law Dictionary