1. (Abbr. yd.) A fundamental unit of length in both the U.S. Customary System and the British Imperial System, equal to 3 feet, or 36 inches (0.9144 meter).
2. Nautical. A long tapering spar slung to a mast to support and spread the head of a square sail, lugsail, or lateen.

[Middle English yerde, stick, unit of measure, from Old English gerd.]

The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.