twilight zone

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.

twilight zone

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

Word History and Origins

Origin of twilight zone¹

First recorded in 1905–10