Crosstree, also known as cross-tree, is a nautical term that describes a horizontal beam or bar that spans across the mast of a ship. It is used to support yards, spars and sails. Crosstree is commonly used in sailing and boating context, however, it has a few synonyms. The most commonly used synonym for crosstree is "crossbar". Other synonyms that can be used interchangeably with crosstree include crossbeam, transverse, traverse, and truss. These synonyms for crosstree can be helpful to use in instances where you want to avoid repetition of the same word, or when you are trying to describe a specific element of a ship's structure.