abatis

noun

1. A means of defense formed by felled trees, or sometimes by bent trees, the ends of whose branches are sharpened and directed outwards, or against the enemy, and more recently fortified with barbed wire.
2. (historical)In the Middle Ages, an officer of the stables who had the care of measuring out the provender; an avenor.
3. In coal-mining, walls of cord-wood piled up crosswise to keep the underground roads open so as to secure ventilation.