Definitions:

1. A horizontal spar on a ship's mast from which sails are traditionally hung. NOUN
   • The captain ordered tha sail lowered from the yardarm as the winds picked up.
2. A part of a ship's mast that extends horizontally or diagonally from the mast typically used to support and spread the ship's sails. NOUN
   • The yardarm creaked and groaned under the weight of the sails, threatening to snap.

Synonyms:

• boom
• crossbeam
• spar
• topmast