tersanctus

from The Century Dictionary.

• noun Same as Sanctus.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Eccl.) 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.