From 'aman; sure; abstract, faithfulness; adverb, truly -- Amen, so be it, truth.
see HEBREW 'aman
H543. amen
אָמֵן adverb verily, truly Deuteronomy 27:15, 26 (12 t.) 1 Kings 1:36; Nehemiah 5:13; Jeremiah 11:5; 28:6 & doxologies 1 Chronicles 16:36 ( = Psalm 106:48); אָמֵן (ו) אָמֵן Numbers 5:22 (P) Nehemiah 8:6, & in the doxologies Psalm 41:14; Psalm 72:19; 8:9Psalm 48. ἀμήν = Amen: אָמֵן אֱלֹהֵי Isaiah 65:16 (twice in verse) God of Amen De Che RVm; compare Revelation 3:14, or God of faithfulness, God of truth (RV) (perhaps read אֹמֶן Che Di).