Merriam-Webster's Collegiate® Dictionary, 11th Edition
AMBUSH
I. verb
Etymology: Middle English embushen, from Anglo-French embuscher, from en in (from Latin in) + busche log, firewood
Date: 14th century
transitive verb to station in ambush, to attack from an ambush ; waylay , intransitive verb to lie in wait ; lurk , ambusher noun ambushment noun
II. noun
Date: 15th century
a trap in which concealed persons lie in wait to attack by surprise, the persons stationed in ambush, an attack especially from an ambush