twilight zone

American  

noun

1. the lowest level of the ocean that light can reach.

2. an ill-defined area between two distinct conditions, categories, etc., usually comprising certain features of both; an indefinite boundary.

   a twilight zone between fantasy and reality.

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twilight zone British  

noun

1. any indefinite or transitional condition or area

2. an area of a city or town, usually surrounding the central business district, where houses have become dilapidated

3. the lowest level of the ocean to which light can penetrate

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Etymology

Origin of twilight zone

First recorded in 1905–10

Example Sentences

They mostly live in the ocean’s twilight zone where light rarely reaches, typically considered 650 to 3,000 feet below the water’s surface.

From Los Angeles Times

The twilight zone teems with life, including krill, squid, fish, octopus, and delicate jelly-like species.

From Science Daily

Instead, as Mr. King notes, they mostly inhabit the “twilight zone,” a place of shifting realities and an infinite number of possible explanations.

From The Wall Street Journal

But Cochran would later describe the case as “a twilight zone of deceit, dishonesty, betrayal and official corruption.”

From Los Angeles Times

The deep sea begins at about 200 meters below sea level, where light starts to diminish in a region called the twilight zone.

From Salon