rook 2 (rk)
n. Abbr. R
A chess piece that may move in a straight line over any number of empty squares in a rank or file. Also called castle.
[Middle English, from Old French roc, from Arabic ruḫḫ, from Persian ruḫ, from Middle Persian rox, ultimately from Middle Indic rahu, raho, nominative of raha- raha-, chariot, from Prakrit ratha-, from Sanskrit rathaḥ (the original form of the rook in the early chess of India being a chariot); see ret- in the Appendix of Indo-European roots.]
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2018 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
The American Heritage Dictionary Blog
Check out our blog, updated regularly, for new words and revised definitions, interesting images from the 5th edition, discussions of usage, and more.