Meaning of crosstree

cross•tree

Pronunciation: (krôs'trē", kros'-), [key]
— n.
  1. either of a pair of timbers or metal bars placed athwart the trestletrees at a masthead to spread the shrouds leading to the mast above, or on the head of a lower mast to support the platform or top.
  2. a heavy crossbeam.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.