The first edition of "The Longer Catechism of the Orthodox, Catholic, Eastern Church", known also as "The Catechism of St. Philaret", did not include the term "metousiosis"; but it was added in the third edition: "In the exposition of the faith by the Eastern Patriarchs, it is said that the word "transubstantiation" is not to be taken to define the manner in which the bread and wine are changed into the Body and Blood of the Lord; for this none can understand but God; but only thus much is signified, that the bread truly, really, and substantially becomes the very true Body of the Lord, and the wine the very Blood of the Lord."[http://www.pravoslavieto.com/docs/eng/Orthodox_Catechism_of_Philaret.htm#ii.xv.iii.i.p41] The official Greek version of this passage (question 340) uses the word "metousiosis".