Synonyms for Dungeon:

n.

belfry, chateau, bell tower, battlements, casbah, chatelaine, castellated, castle, bailey, campanile. dungeon (noun)
keep, donjon.
penal institution (noun)
penal colony.
prison (noun)
collar, penitentiary, keep, cell, handcuff, coop, jug, pillory, pinion, fence, gaol, bridle, oubliette, bastille, jail, cooler, cage, stronghold, brig, harness, irons, reform school, Alcatraz, prison, confine, tether, straight jacket, vise, manacle, penal colony, pen, stockade, San Quentin, shackle, pound, reformatory, vault, lockup, jailhouse.
stockade (noun)
vault.

Other synonyms:

Other relevant words:
donjon, vault, castle.

Usage examples for dungeon

  1. To make her captive and chuck her into my dungeon – A Fool and His Money by George Barr McCutcheon
  2. The castle is enchanted: speak a single word," I said, " and you will find yourself in the dungeon of your own room." – The Flight of the Shadow by George MacDonald
  3. Well, toward evening, the Giant goes down into the dungeon again, to see if his prisoners had taken his counsel; but when he came there he found them alive; and truly, alive was all; for now, what for want of bread and water, and by reason of the wounds they received when he beat them, they could do little but breathe. – Journeys Through Bookland Volume Four by Charles H. Sylvester