From an unused root (meaning to be perverse); (figuratively) silly -- fool(-ish) (man).
H191. evil
אֱוִיל26 adjective (foolish — ׳א Job 5:2 +; plural אֱוִילִים Psalm 107:17 +, etc.; — foolish, Proverbs 29:9 (א ׳אִישׁ) Hosea 9:7 (predicate of prophet); compare Isaiah 35:8, elsewhere
noun masculine fool (always morally bad), who despises wisdom & discipline Proverbs 1:7; 15:5; mocks at guilt 14:9; is quarrelsome 20:3; licentious 7:22; it is folly & useless to instruct him 16:22; 27:22 (19 t. Proverbs); compare also Jeremiah 4:22; Job 5:2-3, Isaiah 19:11; Psalm 107:17.