Any obstruction designed or employed to disrupt, fix, turn, or block the movement of an opposing force, and to impose additional losses in personnel, time, and equipment on the opposing force. Obstacles can exist naturally or can be man-made, or can be a combination of both. (JP 3-15)
OBSTACLE
Meaning of OBSTACLE in English
DOD English dictionary of military terms. Английский словарь военных терминов DOD. 2012