chessman vs rook

chessman and rook both are nouns.

Word	Noun	Adjective	Verb	Adverb
chessman	Yes	No	No	No
rook	Yes	No	Yes	No

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

chessman: any of 16 white and 16 black pieces used in playing the game of chess
rook: (chess) the piece that can move any number of unoccupied squares in a direction parallel to the sides of the chessboard

Other hyponyms of chessman include bishop, castle, king, horse, knight, pawn, queen.

chessman (noun)	rook (noun)
any of 16 white and 16 black pieces used in playing the game of chess	common gregarious Old World bird about the size and color of the American crow
	(chess) the piece that can move any number of unoccupied squares in a direction parallel to the sides of the chessboard

chessman (verb)	rook (verb)
	deprive of by deceit