Webster's Revised Unabridged Dictionary · 1913

Amen

Amen (?; 277) , interj., adv., & n.

[Latin amen, Greek 'amh`n, Hebrew āmēn certainly, truly.]

It is used as a noun, to denote: (a) concurrence in belief, or in a statement; assent; (b) the final word or act; (c) Christ as being one who is true and faithful.

An expression used at the end of prayers, and meaning, So be it. At the end of a creed, it is a solemn asseveration of belief. When it introduces a declaration, it is equivalent to truly, verily.
And let all the people say, Amen. — Bible (KJV) - Psalm cvi. 48
Amen, amen, I say to thee, except a man be born again, he can not see the kingdom of God. — John ii. 3. Rhemish Trans
Collocations (1)
To say amen to , to approve warmly; to concur in heartily or emphatically; to ratify; as, I say Amen to all.

Amen , transitive verb

To say Amen to; to sanction fully.