But this is a word most of us never used in any other context, and for many of us, we had no idea what it meant. It was just that think you say at the end of prayers.
I confess that when I was growing up, I thought it meant something like “over and out.”
The Catechism of the Catholic Church offers a brief explanation of the meaning of the word at the end of its section on the Lord’s Prayer, where it quotes Cyril of Jerusalem:
“Then, after the prayer is over you say ‘Amen,’ which means ‘So be it,’ thus ratifying with our ‘Amen’ what is contained in the prayer that God has taught us” [CCC 2856].
It also says:
By the final “Amen,” we express our “fiat” [Latin, "so be it" or "may it be"] concerning the seven petitions: “So be it” [CCC 2865].
The Catechism also has a longer discussion of the meaning of “Amen” at the end of its section on the Creed:
1062 In Hebrew, amen comes from the same root as the word “believe.” This root expresses solidity, trustworthiness, faithfulness. and so we can understand why “Amen” may express both God’s faithfulness towards us and our trust in him.
1063 In the book of the prophet Isaiah, we find the expression “God of truth” (literally “God of the Amen”), that is, the God who is faithful to his promises: “He who blesses himself in the land shall bless himself by the God of truth [amen].” Our Lord often used the word “Amen,” sometimes repeated, to emphasize the trustworthiness of his teaching, his authority founded on God’s truth.
1064 Thus the Creed’s final “Amen” repeats and confirms its first words: “I believe.” To believe is to say “Amen” to God’s words, promises and commandments; to entrust oneself completely to him who is the “Amen” of infinite love and perfect faithfulness. the Christian’s everyday life will then be the “Amen” to the “I believe” of our baptismal profession of faith:
May your Creed be for you as a mirror. Look at yourself in it, to see if you believe everything you say you believe. and rejoice in your faith each day.
1065 Jesus Christ himself is the “Amen.” He is the definitive “Amen” of the Father’s love for us. He takes up and completes our “Amen” to the Father: “For all the promises of God find their Yes in him. That is why we utter the Amen through him, to the glory of God”:
Through him, with him, in him,
in the unity of the Holy Spirit,
all glory and honor is yours,
God, for ever and ever.
One of the things the Catechism mentions is that Our Lord sometimes repeated the word “Amen.” In some versions of the Bible this is translated “Verily, verily” or “Truly, truly,” but what he actually said was “Amen, amen.”
This was something characteristic of Jesus’ own personal manner of speech.
In any event, the word means more than just “over and out.”