Q. What exactly is the Easter octave?
A. The term octave derives from the Latin word for “eighth” (in music, the eighth note). Octave has two meanings in Catholic liturgy: the eighth day after a feast, reckoning inclusively, or the whole period of these eight days. Today’s Easter Octave is thus the eight days that begin with Easter and continue through the following Sunday.
Initially, the octava dies was associated with the weekly celebration of Christ’s resurrection every “eighth day,” that is, Sunday. The practice of other liturgical octaves was first introduced in the fourth century under the Roman Emperor Constantine for the dedication festivals of two new Christian basilicas. These were one-time events, but eventually certain annual liturgical feasts came to be dignified with an octave. The first such octaves, established in the fourth century, were Easter, Pentecost, and, in the East, Epiphany.
In the following centuries, octaves were multiplied; Christmas, the dedication of churches, and many saints feasts all developed octaves. In more recent times, Church calendar reforms have removed all octaves except Christmas and Easter. The eight days of the Easter Octave are celebrated as solemnities of the Lord, with special readings and prayers for each day. In the Eastern rites, an octave is called an Afterfeast.