OCTAVE

(Lat. octavus.) In Music, an harmonical interval, containing five tones and two semitones, called, by the ancient authors, diapason. Octave, in Ecclesiastical Antiquities, signified the eighth day after a feast, the feast day itself included. Thus, the first Sunday after Easter is the octave of Easter, styled octava infantium, and by other names. The Circumcision (Jan. 1) is the octave natal is domini, the octave of Christmas. The introduction of octaves is said to have been founded on and borrowed from the Jewish ritual. The octave of a feast is sometimes called the Utas, or " the Utasday:" thus, " Wrytyn at Norwich on the Utas-day of Peter and Powll." (Paston Letters, vol. iii., p. 389.) [s. 860]