noun,pluralpen·te·cos·ta·ri·a[pen-dee-kaws-tah-ree-ah; English pen-ti-ko-stair-ee-uh], /ˌpɛn di kɔsˈtɑ ri ɑ; English ˌpɛn tɪ kɒˈstɛər i ə/, pen·te·cos·ta·ri·ons.Greek Orthodox Church.
a service book of offices for the period from Easter to the Sunday after Pentecost.
