From Middle English dongeoun (“keep of a castle; dungeon; abyss, cave, den; whirlpool”), from Anglo-Norman donjun (“keep of a castle; keep used as a prison; dungeon”) and continental Old French donjon (“keep of a castle”), from Vulgar Latin *dominiōnem, seemingly derived from Latin dominus (“master, lord”) perhaps via some figurative sense like “dominant building”. Doublet of donjon. The sense of “prison (associated with a castle)”, first attested in Anglo-Norman (13th c.) and apparently never in continental Old French, likely developed in combination with Old English dung (“underground prison cell”), whence Middle English donge (“pit, abyss”, senses that are also attested for Middle English dongeoun). The game term has been popularized by Dungeons & Dragons.
1
An underground prison or vault, typically built underneath a castle.
Year after year he lay patiently in a dungeon.1911, Thomas Babington Macaulay, “Bunyan, John”, in 1911 Encyclopædia Britannica:
2
The low area between two drumlins.
3
Obsolete The main tower of a motte or castle; a keep or donjon.
From Middle English dongeoun (“keep of a castle; dungeon; abyss, cave, den; whirlpool”), from Anglo-Norman donjun (“keep of a castle; keep used as a prison; dungeon”) and continental Old French donjon (“keep of a castle”), from Vulgar Latin *dominiōnem, seemingly derived from Latin dominus (“master, lord”) perhaps via some figurative sense like “dominant building”. Doublet of donjon. The sense of “prison (associated with a castle)”, first attested in Anglo-Norman (13th c.) and apparently never in continental Old French, likely developed in combination with Old English dung (“underground prison cell”), whence Middle English donge (“pit, abyss”, senses that are also attested for Middle English dongeoun). The game term has been popularized by Dungeons & Dragons.
1
To imprison in a dungeon.
Of every act of severity, of every bold violation of the constitution, of every bill for dungeoning and gagging the people, of every tax, of every loan, of all that set frugality at defiance, and that mocked at mercy, these men had been either the authors or the most strenuous supporters […]1830, William Cobbett, History of the Regency and Reign of King George the Fourth: