castle vs dungeon

castle and dungeon both are nouns.

Word	Noun	Adjective	Verb	Adverb
castle	Yes	No	Yes	No
dungeon	Yes	No	No	No

castle (noun)	dungeon (noun)
interchanging the positions of the king and a rook	the main tower within the walls of a medieval castle or fortress
a large building formerly occupied by a ruler and fortified against attack	a dark cell (usually underground) where prisoners can be confined
(chess) the piece that can move any number of unoccupied squares in a direction parallel to the sides of the chessboard
a large and stately mansion

castle (verb)	dungeon (verb)
move the king two squares toward a rook and in the same move the rook to the square next past the king