281. amen, am-ane'; of Heb. or. [H543]; prop. firm, i.e. (fig.) trustworthy; adv. surely (often as interj. so be it): --amen, verily.
And then the Hebrew from whence the Greek comes: 543. 'amen, aw-mane'; from H539; sure; abstr. faithfulness; adv. truly:--Amen, so be it, truth.
And original Hebrew from which the 'amen is derived:
539. aman, aw-man'; a prim. root; prop. to build up or support; to foster as a parent or nurse; fig. to render (or be) firm or faithful, to trust or believe, to be permanent or quiet; mor. to be true or certain; once (Isa. 30:21; by interch. for H541) to go to the right hand:--hence assurance, believe, bring up, establish, + fail, be faithful (of long continuance, stedfast, sure, surely, trusty, verified), nurse, (-ing father), (put), trust, turn to the right.