Meaning of chesstree

chess•tree

Pronunciation: (ches'trē"), [key]
— n. Naut.
  1. (in the 17th and 18th centuries) a wooden fastening with one or more sheaves, attached to the topside of a sailing vessel, through which the windward tack of a course was rove.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.