Meaning

noun the main tower within the walls of a medieval castle or fortress

noun a dark cell (usually underground) where prisoners can be confined

originFrom 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…

Etymology from Wiktionary, CC BY-SA 3.0