In the New Testament we have various words translated "fool," "foolish," "folly," etc., in the ordinary acceptation of these terms; aphron, "mindless," "witless" (Lu 11:40; 12:20; 1Co 15:36); aphrosune, "want of mind or wisdom" (2Co 11:1; Mr 7:22); anoia, "want of understanding" (2Ti 3:9); moraino, "to make dull," "foolish" (Ro 1:22; 1Co 1:20); moros, "dull," "stupid" (Mt 7:26; 23:17; 25:2; 1Co 1:25,27); moria, "foolishness" (1Co 1:18, etc.); morologia, "foolish talk" (Eph 5:4).
In Mt 5:22 our Lord says: "Whosoever shall say (to his brother), Thou fool (more), shall be in danger of the hell of fire (the Gehenna of fire)." Two explanations of this word are possible: (1) that it is not the vocative of the Greek moros--a word which was applied by Jesus Himself to the Pharisees (Mt 23:17,19), but represents the Hebrew morah, "rebel" applied in Nu 20:10 by Moses to the people, "ye rebels" (for which he was believed to be excluded from the promised land; compare Nu 20:12; hence, we have in the Revised Version, margin "or moreh, a Hebrew expression of condemnation"); or (2) that, as our Lord spake in the Aramaic it is the Greek translation of a word representing the Hebrew nabhal, "vile, or worthless fellow," atheist, etc. (Ps 14:1; 53:1).
W. L. Walker