Trisagion

Trisagion, or TRISHAGION (Gr. tris, 'thrice,' and hagios, 'holy'), one of the doxologies in use in the Greek Church which is repeated in the form of versicle and responses by the choir in certain parts of the liturgy. The words of the Trisagion are: 'O holy God, holy and mighty, holy and immortal, have mercy on us!' This doxology occurs in the Constantinopolitan and Syriac liturgies, in the Good Friday service of the 'adoration of the Cross,' and in the ferial prayers at Prime for penitential days.