The Roman Catholic doctrine of "transubstantiation" is condemned at the 1691 Orthodox Synod in Constantinople.

[Blog commentary: The synods of the 17th century were responding to Protestants, who denied that there was any real change in the Eucharist. That is why the Synod of Jerusalem (1672)  says that there is "transubstantiation". But soon the Orthodox realized that the Romans Catholics mean something very specific with this term and that they use aristotelian concepts of substance and accident. So, the synod of 1691 replies that it is neither just a symbol (for there is a real change) nor the roman catholic aristotelian explanation. That is, we believe according to apostolic teaching that there is a real change. But the aristotelian definition is simply wrong (and this is the official Roman definition of the Lateran Council of 1215).]

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CONCILIUM CONSTANTINOPOLITANANUM 1691

SYNOD OF CONSTANTINOPLE 1691 

The Council's chief decision was on Transubstantiation (μετουσίωσις - metousíōsis), the theory by which the bread and wine change substance during consecration. The doctrine was known in the West and had developed within an Aristotelian framework, according to which the substance would change, but the attributes would not. This would explain why the communicant does not physically perceive a change. The first official statement of the doctrine is found in the Fourth Lateran Council (1215). (1) The Latin doctrine of Transubstantiation becomes prominent chiefly with Thomas Aquinas (1225-1274). (2) The Protestant reformation attacked the doctrine. Luther referred to it as Aristotelian Pseudo-Philosophy, (3) while the thirty-nine articles of religion of the Anglican Church (1563) rejected it. (4) Thus, both Catholics and Protestants agreed that there is a change which takes place during the Eucharist, but had divergent opinions on the nature of this change. 

The occasion of the Synod was the publication of the Confession of Dositheos in 1690. In it, the term metousios is accepted. The opponent of the term was Ioannes Karyophylles (1600-1692), who wrote a treatise about the Eucharist that denied the term 'transubstantiation':

(5). This dispute may be interpreted as the end of a series of synods in Constantinople (1638, 1642), Jerusalem (1672), and the present one, which dealt with the relation between Protestant ideas and the Orthodox Church. It also dealt with the relation between Moldavia and Constantinople in this period. It is important to keep in mind that these synods took place at a time of restructuring of the Ottoman influence and power, between the end of the Persian-Ottoman wars (with the Treaty of Zuhab of 1639) and the siege of Vienna in 1683. 

It was convened by Callinicus II Ecumenical Patriarch (1689-1693: 1694-1702) and it defined Transubstantiation as a change. Moreover, it explains that this idea does not derive front the Western Churches (from the Latins), but finds its origins in Greek theology. The text explicitly refers to Gennadios, Patriarch of Constantinople (1454-1464). He employed the term μετουσίωσις (metousíōsis/transubstantiation) to refer to the nature of Christ itself. Indeed, he seems to understand the term as meaning μεταβολή (metabolē/change). (6) The idea that it was a 'change' is indeed traditional. However, the term μετουσίωσις (metousíōsis/transubstantiation) appears as a translation of the term 'transubstantiation' and it had been attacked for this reason. What is clear is that the term as understood by this Synod does not seem to imply the distinction substance/accidents which was important for the Lateran Council of 1215. 

The edition follows that of Karmiris'.

Source: Corpus Christianorum Conciliorum Oecumenicorum Generaliumque Decreta. The Great Councils of the Orthodox Churches: From Constantinople 861 to Moscow 2000