A cry of praise or adoration to god in liturgical use among the Jews, and said to have been shouted in recognition of the Messiahship of Jesus on his entry into Jerusalem; hence since used in the Christian Church
(interjection.) before 12th century. From Latin osanna, hosanna, from Ancient Greek ὡσαννά (hosanna), from Classical Hebrew הוֹשַׁע־נָא (hōsha‘-nā, “please save”).