noun: (ecology) An area of the ocean where oxygen levels are too low to support life, especially as a result of pollution.
noun: (telecommunications) A region where mobile phones do not operate because there is no base station or repeater nearby.
noun: (sports, gridiron football) Part of the field, entered by a player when they are on their opponent's side of the field but kicking a field goal would probably be unsuccessful and punting the ball would not dramatically change field position.
noun: (military, historical) Area near a fortification that is relatively sheltered from defending fire, because direct fire from other parts of the walls cannot be directed around a curved wall.
noun: (video games) A region within the player's viewpoint that is less sensitive to small movements, aiding accurate firing of weapons etc.
