dungeon (n.)

early 14c., dongoun, "inner tower, keep, or stronghold of a castle," also "underground prison cell in a donjon of a castle;" see dungeon.

mid-13c., daunger, "arrogance, insolence;" c. 1300, "power of a lord or master, jurisdiction," from Anglo-French daunger, Old French dangier "power, power to harm, mastery, authority, control" (12c., Modern French danger), alteration (due to association with damnum) of dongier, from Vulgar Latin *dominarium "power of a lord," from Latin dominus "lord, master," from domus "house" (from PIE root *dem- "house, household").

Modern sense of "risk, peril, exposure to injury, loss, pain, etc." (from being in the control of someone or something else) evolved first in French and was in English by late 14c. For this, Old English had pleoh; in early Middle English this sense is found in peril. For sound changes, compare dungeon, which is from the same source.

Proto-Indo-European root meaning "house, household." It represents the usual Indo-European word for "house" (Italian, Spanish casa are from Latin casa "cottage, hut;" Germanic *hus is of obscure origin).

It forms all or part of: Anno Domini; belladonna; condominium; dame; damsel; dan "title of address to members of religious orders;" danger; dangerous; demesne; despot; Dom Perignon; domain; dome; domestic; domesticate; domicile; dominate; domination; dominion; domino; don (n.) "Spanish, Italian, and Portuguese title of respect;" Donna; dungeon; ma'am; madam; madame; mademoiselle; madonna; major-domo; predominant; predominate; timber; toft.

It is the hypothetical source of/evidence for its existence is provided by: Sanskrit damah "house;" Avestan demana- "house;" Greek domos "house," despotēs "master, lord;" Latin domus "house," dominus "master of a household;" Armenian tanu-ter "house-lord;" Old Church Slavonic domu, Russian dom "house;" Lithuanian dimstis "enclosed court, property;" Old Norse topt "homestead."