A stamp commemorating Arbor Day.Licensed from iStockPhoto
Webster's New World College Dictionary Copyright © 2010 by Wiley Publishing, Inc., Cleveland, Ohio.
a tree-planting day observed individually by the states of the U.S., usually in spring
Used by arrangement with John Wiley & Sons, Inc.
The American Heritage® Dictionary of the English Language, 4th edition Copyright © 2010 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
An unofficial holiday observed in all 50 states of the United States, most often on the last Friday in April, for the public planting of trees.