The word amen or ameen (in Hebrew אָמֵן, Greek ἀμήν, Arabic آمِينَ Armenian ամէն) can be traslated with “truth” or “truly”.
The specific Hebrew word amen (’amen) appears to be derived from a related verb ’aman , which means “he confirmed, supported, or upheld.” This verb is also associated with the Hebrew word for truth (’emet ), which carries the idea of certainty.

21 When Jesus had thus said, he was troubled in spirit, and testified, and said, Verily, verily [Amen, amen] , I say unto you, that one of you shall betray me.
(Gospel according to Jhon 13, 21)

Is a declaration of affirmation found in the Bible and in the Jewish, Christian, and Muslim worship and traditions as a concluding affermative word or response to prayers.
Common English translations of the word amen include “verily” and “truly”. It can also be used colloquially to express strong agreement, as in, for instance, amen to that.

The usage of Amen, meaning “so be it”, as found in the early scriptures of the Bible is said to be of Hebrew origin; however, the basic triconsonantal root from which the word was derived is common to a number of languages, such as Aramaic, in the Semitic branch of the Afroasiatic languages. The word was imported into the Greek of the early Church from Judaism. From Greek, amen entered the other Western languages. According to a standard dictionary etymology, amen passed from Greek into Late Latin, and thence into English. Rabbinic scholars from medieval France believed the standard Hebrew word for faith emuna comes from the root amen. Although in English transliteration they look different, they are both from the root aleph-mem-nun. That is, the Hebrew word amen derives from the same ancient triliteral Hebrew root as does the verb ʾāmán.
In Arabic, the word is derived from its triliteral common root word ʾĀmana (Arabic: آمن‎), which has the same meanings as the Hebrew root word.
In French, the Hebrew word amen is sometimes translated as Ainsi soit-il, which means “So be it.”

Old Testament

The word first occurs in the Hebrew Bible in Numbers 5, 22 when the Priest addresses a suspected adulteress and she responds “Amen, Amen”. Overall, the word appears in the Hebrew Bible 30 times.

Three distinct Biblical usages of amen may be noted:

1. Initial amen, referring back to words of another speaker and introducing an affirmative sentence, e.g. 1 Kings 1, 36.
2. Detached amen, again referring to the words of another speaker but without a complementary affirmative sentence, e.g. Nehemiah 5, 13.
3. Final amen, with no change of speaker, as in the subscription to the first three divisions of Psalms.

New Testament

There are 52 amens in the Synoptic Gospels and 25 in John. The five final amens (Matthew 6, 13 ; 28, 20 ; Mark 16, 20 ; Luke 24, 53 & John 21,25), which are wanting in certain manuscripts, simulate the effect of final amen in the Psalms. All initial amens occur in the sayings of Jesus. These initial amens are unparalleled in Hebrew literature, according to Friedrich Delitzsch, because they do not refer to the words of a previous speaker but instead introduce a new thought.

The uses of amen (“verily” or “I tell you the truth”, depending on the translation) in the Gospels form a peculiar class; they are initial, but often lack any backward reference. Jesus used the word to affirm his own utterances, not those of another person, and this usage was adopted by the Christian Church. The use of the initial amen, single or double in form, to introduce solemn statements of Jesus in the Gospels had no parallel in Jewish practice.

In the King James Bible (KJV), the word amen is preserved in a number of contexts. Notable ones include:

• The catechism of curses of the Law found in Deuteronomy 27
• A double amen (“amen and amen”) occurs in Psalm 89 (Psalm 41, 13 ; 72, 19 & 89, 52) to confirm the words and invoke the fulfillment of them
• Amen occurs in several Doxology formulas in Romans 1, 25 ; 9, 5 ; 11, 36 ; 15, 33 and several times in Chapter 16. It also appears in doxologies in the Psalms (41, 14 ; 72, 19 ; 89, 53 & 106, 48). This liturgical form from Judaism
• It concludes all of Paul’s general epistles
• In Revelation 3, 14, Jesus is referred to as, “the Amen, the faithful and true witness, the beginning of GOD’s creation.” The whole passage reads as “And unto the angel of the church of the Laodiceans write; These things saith the Amen, the faithful and true witness, the beginning of the creation of GOD;”
• Amen concludes the New Testament at Rev. 22, 21

In Islam

In Judaism

Although amen, in Judaism, is commonly stated as a response to a blessing, it is also often used as an affirmation of any declaration.
Jewish rabbinical law requires an individual to say amen in a variety of contexts.
With the rise of the synagogue during the Second Temple period, amen became a common response, especially to benedictions. It is recited communally to affirm a blessing made by the prayer reader. It is also mandated as a response during the kaddish Doxology. The congregation is sometimes prompted to answer ‘amen’ by the terms ve-‘imru (Hebrew: ואמרו‎) = “and [now] say (pl.),” or, ve-nomar (ונאמר) = “and let us say.” Contemporary usage reflects ancient practice, as early as the 4th century BCE, Jews assembled in the Temple responded ‘amen’ at the close of a Doxology or other prayer uttered by a priest. This Jewish liturgical use of amen was adopted by the Christians, but actually the Jewish law also requires individuals to answer amen whenever they hear a blessing recited, even in a non-liturgical setting.

In Christianity

The use of “amen” has been generally adopted in Christian worship as a concluding word for prayers and hymns and an expression of strong agreement. The liturgical use of the word in apostolic times is attested by the passage from 1 Corinthians cited above, and Justin Martyr (c. 150) describes the congregation as responding “amen” to the benediction after the celebration of the Eucharist. Its introduction into the baptismal formula (in the Eastern Orthodox Church it is pronounced after the name of each person of the Trinity) was probably later.

In Isaiah 65, 16, the authorized version has “the GOD of truth” (“the GOD of amen” in Hebrew). Jesus often used amen to put emphasis to his own words (translated: “verily” or “truly”). In John’s Gospel, it is repeated, “Verily, verily”(or “Truly, truly”). Amen is also used in oaths (Numbers 5, 22 ; Deuteronomy 27, 15–26 ; Nehemiah 5, 13 ; 8, 6 & 1Chronicles 16,36) and is further found at the end of the prayer of primitive churches (1Corinthians 14,16).

In some Christian churches, the “amen corner” or “amen section” is any subset of the congregation likely to call out “Amen!” in response to points in a preacher’s sermon.

Amen is also used in standard, international French, but in Cajun French Ainsi soit-il (“so be it”) is used instead.
Amen is used at the end of the LORD’s Prayer, which is also called the Our FATHER or the PATER Noster.

References

• Harper, Douglas. “amen”. Online Etymology Dictionary. Retrieved 20 August 2007.
• “amen – definition of amen in English by Oxford Dictionaries”. oxforddictionaries.com. Retrieved 2 September 2015.
• “Amen”. Jewish Encyclopedia. Archived from the original on 16 February 2008. Retrieved 19 February 2008.