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). See Table at measurement.
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.]