Tersanctus
From BiblePortal Wikipedia
Webster's Dictionary [1]
(n.) An ancient ascription of praise (containing the word "Holy" - in its Latin form, "Sanctus" - thrice repeated), used in the Mass of the Roman Catholic Church and before the prayer of consecration in the communion service of the Church of England and the Protestant Episcopal Church. Cf. Trisagion.
The Nuttall Encyclopedia [2]
The ascription of praise, Holy, Holy, Holy, preliminary to the consecrating prayer in Holy Communion.
