ambush (n.)

late 15c., embushe, "troops concealed to surprise an enemy," from the English verb or from Old French embusche "an ambush, a trap" (13c., Modern French embûche), from embuschier "to lay an ambush" (see ambush (v.)). Non-military sense from 1570s. Figurative use by 1590s. Earlier was ambushment (late 14c.), from Old French embuschement, Medieval Latin imboscamentum.

ambush (v.)

c. 1300, from Old French embuschier (13c., Modern French embûcher) "to hide, conceal, lay an ambush," from en- "in" (from PIE root *en "in") + busch "wood," which is apparently from Frankish *busk "bush, woods," or a similar Germanic source (see bush (n.)). The notion probably is "hide in the bush," or "lure into the bush." Related: Ambushed; ambushing.