[pen-dee-kaws-tah-ree-awn; English pen-ti-ko-stair-ee-on]

noun, plural pen·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.

Origin of pentecostarion

< Late Greek pentēkostárion, equivalent to Greek pentēkost(ḗ) Pentecost + -arion < Latin -ārium -ary Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019