noun
Literary or poetic term for deep gloom or darkness. Rarely used in everyday speech; more common words are 暗闇 (くらやみ) or 闇 (やみ).
冥暗の森の中、一筋の光も差さなかった。
In the gloomy forest, not a single ray of light penetrated.
Compound of 冥 (めい, dark, gloomy) and 暗 (あん, darkness). The exact historical derivation is uncertain; the spelling is conventionally associated with deep gloom.