Apodosis

Apodosis (ἀπόδοσις, return). When the commemoration of a festival is prolonged over several days, the last day of this period is called in the Greek calendar the "apodosis" of the festival. For instance, on the Thursday before Pentecost is the apodosis of the Ascension. In this case, and in some others (for instance, the Exaltation of the Cross and the Transfiguration), the apodosis coincides with the octave; but this is not always the case. Sometimes the period is more than an octave. Easter-day, for instance, has its apodosis on the eve of the Ascension, but generally it is less; the Nativity of the 'Theotokos (Sept. 8), for instance, has its apodosis Sept. 12.