Of or pertaining to Greece or the Greeks; Grecian. Greek calends. See Calends. Greek Church, the Eastern Church; that part of Christendom which separated from the roman or western Church in the ninth century. It comprises the great bulk of the Christian population of Russia (of which this is the established church), Greece, Moldavia, and Wallachia. The greek Church is governed by patriarchs and is called also the byzantine Church. Greek cross. Greek fire, a combustible composition which burns under water, the constituents of which are supposed to be asphalt, with niter and sulphur. Greek rose, the flower campion.