Trisagion
noun
Tris·agion
trēˈsȧyȯn
plural Trisagia
-yȧ
1
: a hymn to or invocation of God as the thrice holy
the Trisagion of Isa 6:3
2
: a requiem service of the Eastern Church
Word History
Etymology
Middle Greek, from neuter of Late Greek trisagios thrice holy, from Greek tris- + hagios holy