dungeonyoudaoicibaDictYouDict[dungeon 词源字典]
dungeon: [14] In common with a wide range of other English words, including danger, demesne, dominion, domino, and don, dungeon comes ultimately from Latin dominus ‘lord, master’. Derived from this was dominium ‘property’ (source of English dominion), which in postclassical times became dominiō or domniō, meaning ‘lord’s tower’.

In Old French this became donjon, the term for a ‘castle keep’, and eventually, by extension, a ‘secure (underground) cell’. English acquired the package in the 14th century, but in common usage has retained only the latter sense, in the adapted Middle English spelling (although the original Old French form remains in use as a technical term for a ‘castle keep’).
=> dame, danger, demesne, dominion, dominate[dungeon etymology, dungeon origin, 英语词源]
dungeon (n.)youdaoicibaDictYouDict
c. 1300, "great tower of a castle," from Old French donjon "great tower of a castle" (12c.), from Gallo-Roman *dominionem, from Late Latin dominium, from Latin dominus "master" (of the castle; see domain). Sense of "castle keep" led to "strong (underground) cell" in English early 14c. The original sense went with the variant donjon.