Ite, missa est

[6] Fortescue (1910) cites more "fanciful" etymological explanations, notably a latinization of Hebrew matsâh (מַצָּה) "unleavened bread; oblation", a derivation favoured in the 16th century by Reuchlin and Luther.

[7] Overlooked are two forms of dismissal of the Aquileian Rite, one used for Major Double Feasts and another for Major Solemnities of the Blessed Virgin Mary, respectively, "Ite benedicti et electi in viam pacis: pro vobis Deo Patri hostia missa est" and "Ite benedicti et electi in viam pacis: pro vobis Mariae Filius hostia missa est" as recorded in Migne's Patrologia Latina 99 which presents a Mass for the feast of St. Paulinus II of Aquileia excerpted from the Aquileian Missal of 1519.

Noteworthy is the fact missa est is used as a past perfect verb in the passive voice with hostia as its subject.

[9] After the twelfth century, accretions began to be added to the Mass after the "Ite, missa est", changing it from a dismissal to a mere formula without relation to actuality.

With the reform of Pope Paul VI "Ite, missa est" returned to its function as a dismissal formula.

Being sung by an individual (ideally the deacon), not by a choir, it cannot be part of a polyphonic musical setting of the Mass.