/dun"jeuhn/ , n.
1. a strong, dark prison or cell, usually underground, as in a medieval castle.
2. the keep or stronghold of a castle; donjon.
[ 1250-1300; ME dungeo ( u ) n, dongeoun, dungun donjon domnion- (s. of * domnio ) keep, mastery, syncopated var. of * dominion- DOMINION ]