Ave verum corpus is a short Eucharistic hymn dating from the 14th century and attributed to Pope Innocent VI (d. 1362), which has been set to music by various composers. During the Middle Ages it was sung at the elevation of the host during the consecration. It was also used frequently during Benediction of the Blessed Sacrament.

The hymn's title means "Hail, true body", and is based on a poem deriving from a 14th-century manuscript from the Abbey of Reichenau, Lake Constance. The poem is a meditation on the Catholic belief in Jesus's Real Presence in the sacrament of the Eucharist, and ties it to Catholic ideas on the redemptive meaning of suffering in the life of all believers.

Wolfgang Amadeus Mozart's setting of Ave Verum Corpus was written in 1791, to celebrate the feast of Corpus Christi.

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The text is in Latin, and reads: Ave verum corpus, Natum de Maria Virgine, Vere passum, immolatum In cruce pro homine, Cuius latus perforatum Unda fluxit et sanguine, Esto nobis praegustatum In mortis examine.

A translation into English is: Hail the true body, Born of the Virgin Mary, Truly suffered, sacrificed On the Cross for mankind, Whose pierced side Flowed with water and blood, Let it be for us, in consideration, A foretaste of death.

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(This information has been adapted from Wikipedia) (less info)