ambush (v.)
c.1300, from Old French embuscher (13c., Modern French embûcher) "to lay an ambush," from en- "in" + busch "wood," apparently from Frankish *busk "bush, woods" (see bush (n.)). Related: Ambushed; ambushing.
ambush (n.)
late 15c., embushe, from the English verb or from Middle French embusche, from Old French embuscher (see ambush (v.)). Earlier was ambushment (late 14c.). Figurative use by 1590s.