Definition of amen:
at the end of prayers: so be it; at the end of a creed
or in Biblical translations: truly
"amen, amen, I say to thee, except a man be born again, he can not see the kingdom of God. -- John ii. 3. Rhemish Translation"
an expression of strong agree
an instance of saying 'amen'; a title of Christ; the Faithful One (especially with reference to Revelation 3:14)