hosanna (interj.)

Old English osanna, via Medieval Latin hosanna, Late Latin osanna, and Greek ossana, hosanna, from Hebrew hosha'na, probably a shortening of hoshi'ah-nna "save, we pray" (see Psalm cxviii.25), from imperative of y-sh- (compare yeshua "salvation, deliverance, welfare," for which see Joshua) + emphatic particle -na.

Originally an appeal for deliverance; used in Christian Church as an ascription of praise, because when Jesus entered Jerusalem this was shouted by Galilean pilgrims in recognition of his messiahhood (Matthew xxi.9, 15, etc.).