dead zone

1 :  an area of water (as in a lake or ocean) in which the level of dissolved oxygen is so depleted (as by the decay of an algal bloom) that most life cannot be sustained This is the Gulf of Mexico's “dead zone,” which last summer reached the size of the state of New Jersey. — Carol Kaesuk Yoon, New York Times, 20 Jan. 1998 In certain conditions, oxygen levels in the water can fall to dangerously low levels, creating what is commonly known as a dead zone. Fast-swimming creatures like fish can flee, but most bottom dwellers, such as shellfish, are likely to die. — Mark Schrope, New Scientist, 9 Dec. 2006

2 :  an area where cell phone reception is very poor or unavailable The Sleek has even improved reception near my local gym, which used to be a dead zone. — Terry Gardner, Chicago Tribune, 5 Oct. 2010 “It would definitely be foolhardy to come into this wilderness park and expect cell coverage,” said [park ranger Jon] Preston, who gets reception on his phone about a mile up the trail from the Hoh Rain Forest Visitor Center. “Beyond that, you're in a dead zone … .” — Rob Ollikainen, Peninsula Daily News (Port Angeles, Washington), 4 Sept. 2010