# twilight zone

> English word · Noun

## Definitions
1. A moving line that divides the daylit side and the dark night side of a planetary body.
2. A region or context located in between others and therefore not subject to their norms.
3. A deteriorating area surrounding a central business district.
4. Synonym of mesopelagic zone (“the part of the ocean where there is very minimal light, located below the photic epipelagic zone but above the aphotic bathypelagic zone.”).

## Etymology
Because such a zone (in the literal sense of the term) is twilit; see twilight § Etymology.

## Source
Compiled from Wiktionary via kaikki.org (CC BY-SA). Data vintage: 2026-05-06.
Canonical page: https://plainspell.com/en/word/twilight-zone