utas

The octave of a festival, a legal term, or other particular occasion—that is, the space of eight days after it, or the last day of that space of time: as, the utas of Saint Hilary.

Hence—2. Bustle; stir; unrestrained jollity or festivity, as during the octave of a festival.

The eighth day after any term or feast; the octave

Hence, festivity; merriment.

The octave, or seventh day after a festival (i.e., the eighth day counting inclusively, in the ancient Roman way).