Hosanna comes from the Hebrew of Psalm 118 — save now, we beseech thee, O LORD — a cry for rescue that, over time, became also a shout of praise and welcome. By the time the crowds waved palm branches at Jesus' entry into Jerusalem, hosanna carried both meanings at once: a plea for the Messiah to save, and a joyful acclamation of the one who could.
When the crowds cried Hosanna to the Son of David, they were hailing Jesus as the promised deliverer, quoting the very psalm the pilgrims sang at Passover. The irony is that within days the same city would call for his crucifixion — yet he would save them, and the world, in a way the palm-wavers never imagined: not from Rome, but from sin.
Hosanna in Scripture
And the multitudes that went before, and that followed, cried, saying, Hosanna to the son of David: Blessed is he that cometh in the name of the Lord; Hosanna in the highest.