castle vs long castle

castle and long castle both are nouns.

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

As nouns, long castle is a hyponym of castle; that is, long castle is a word with a more specific, narrower meaning than castle:

Other hyponyms of castle include castling short, short castle, short castling, castling long, long castling.

castle (noun)	long castle (noun)
interchanging the positions of the king and a rook	castling on the queenside.
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

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