The act of concealing yourself and lying in wait to attack by surprise(noun)
Waiting in concealment; in ambush(adjective)
WordNet. Princeton University. 2010.
Use "lying in wait" in a sentence
"At which moment, thethousand-strong American force that had been lying in wait in the mudbrick houses and sewers of Luxorbehind the European ambush force moved in."
"There was always the danger of a Flighter lying in wait and jumping out at me through a nearby window before I had time to react, but it was better than running down the street for all to see."
"In case the Boston Strangler took a serious wrong turn and is lying in wait for me?"