a day, varying in date but always in the spring, observed in certain states of the U.S. by the planting of trees.
Origin of Arbor Day
An Americanism dating back to 1870–75
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
Examples from the Web for arbor day
He made no reply, going on carefully with his arbor-day practice.V. V.'s Eyes|Henry Sydnor Harrison