Abatis, Abattis or Abbattis (a French word meaning a heap of material thrown), a term in field fortification for an obstacle formed of the branches of trees laid in a row, with the tops directed towards the enemy and interlaced or tied with wire.
The abatis is used alone or in combination with wire entanglements and other obstacles.
Also, a form of giant abatis, using whole trees instead of branches, can be used as an anti-tank obstacle.