Question: What is a doxology? Why is the "amen" said by all present at the conclusion of the Eucharistic Prayer called the "Great Amen"?
Answer: A doxology is typically an expression of praise said or sung to the Holy Trinity, the Father, the Son and the Holy Spirit.
Examples: "Through him, with him, and in him, in the unity of the Holy Spirit, all glory and honor is yours, almighty Father, for ever and ever." follows the consecration. "For the kingdom, the power, and the glory are yours, now and for ever" follows the Lord's Prayer.
Amen is a Hebrew word that means "so be it". Saying amen means that we agree. The Great Amen is the response of the faithful to the Eucharistic prayer offered by the priest on their behalf and to the sacrifice of Jesus offered to the Father. It is called the "Great" Amen because there should be a strong agreement given to this prayer and sacrifice of praise and thanksgiving.