long castling vs castle

long castling and castle both are nouns.

Word	Noun	Adjective	Verb	Adverb
long castling	Yes	No	No	No
castle	Yes	No	Yes	No

As nouns, castle is a hypernym of long castling; that is, castle is a word with a broader meaning than long castling:

Other hypernyms of long castling include castling.

long castling (noun)	castle (noun)
castling on the queenside.	interchanging the positions of the king and a rook
	a large building formerly occupied by a ruler and fortified against attack
	(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

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