Definitions for palm sunday
Random House Webster's College Dictionary
the Sunday before Easter, celebrated in commemoration of Christ's triumphal entry into Jerusalem.
Origin of Palm Sunday:
Sunday before Easter
The Sunday before Easter, commemorating Christ's entry into Jerusalem, when palm fronds were strewn before him.
the Sunday next before Easter; -- so called in commemoration of our Savior's triumphal entry into Jerusalem, when the multitude strewed palm branches in the way
The Nuttall Encyclopedia
the Sunday before Easter, is so called from its being commemorative of Christ's triumphal entry into Jerusalem; it is observed by the Greek and Roman Churches; in the latter palm branches are blessed by the priest before mass, carried in procession, distributed to the congregation, carried home by them, and kept throughout the year.