Euchologion \Eu`cho*lo"gi*on\, Euchology \Eu*chol"o*gy\, n. [NL. euchologion, Gr. ? prayer book; ? prayer, vow (fr. ? to pray) + ? to say, speak.] (Eccl.) A formulary of prayers; the book of offices in the Greek Church, containing the liturgy, sacraments, and forms of prayers. [1913 Webster]