1. Protection from hostile observation and fire provided by an obstacle such as a hill, ridge, or bank. 2. A vertical distance by which a position is concealed from enemy observation. 3. To shield from enemy fire or observation by using natural or artificial obstacles.
Found on http://www.encyclo.co.uk/local/20524
De`fi·lade' transitive verb [ imperfect & past participle Defiladed ; present participle & verbal noun Defilading .] [ Confer French défiler to defile, and défilade act of defiling. See 1st Defile .] (Mil.) Found on http://www.encyclo.co.uk/webster/D/23