From BiblePortal Wikipedia

Hastings' Dictionary of the New Testament [1]

Foolishness —In the Sermon on the Mount, Jesus points out the grave sin of saying to our brother, ‘Thou fool’ (μωρέ,  Matthew 5:22). When He likened His critics to children in the market-place who would play at neither a sad nor a merry game ( Matthew 11:16-19), was He not saying in His heart, ‘Ye fools’? But anger and contempt are the sources of the former; wonder and pity, mingled with indignation, shape the latter.* [Note:  Luke 24:25Σ ἁνοητοι ‘O foolish men’ [AV ‘O fools’ is too harsh]. See preceding article.] He who knew what was in man had occasion to marvel at the foolishness of men. That foolishness is a ruinous self-deception in spiritual things. He points out this folly in these classes:

1. The foolishness of worldly men .—God said to the rich man, ‘Thou fool’ (ἄφρων,  Luke 12:20). The parable ( Luke 12:16-21) was inspired by a request which showed to Christ a heart so absorbed in thought of material good that it could not listen to His message. That fact gives us the point of view from which to consider the parable. The good of life cannot be in earth’s riches which pass from owner to owner, and whose possession is at the mercy of death, which is only an accident to the immortal soul ( Luke 12:20). Covetousness, a man’s absorption in heaping up and enjoying things, is folly in so far as it hinders him from attaining to the true riches, treasure of the soul laid up with God ( Luke 12:15; Luk_12:21).

2 . The foolishness of the formalist , who shuts his eyes (μωροὶ καὶ τυφλοί) to the spiritual side, the inward consecration which gives meaning and value to conduct or to things ( Luke 11:40,  Matthew 23:17).

3 . The foolishness of the religious .—This thought occurs more frequently. It is a mark of our Lord’s teaching that it is concerned rather with the subtler forms of evil which beset the religious class. He assumes that those sins of sense and temper which all the world condemns, need no condemnation from Him. This foolishness consists generally in a lack of seriousness, a lack of whole-heartedness and simplicity in faith and conduct. There are those who hear His words and do them not ( Matthew 7:26-27). These are believers whose whole spirit is a contradiction, children of faith in mind, children of unfaith in conduct. This foolishness of believers is the formative thought of the parables of the Unjust Steward ( Luke 16:3-9) and of the Ten Virgins ( Matthew 25:1-13). The meaning of the former parable is said by Jesus to be, that the children of this world are wiser in their generation than the children of light. That wisdom consists in greater singleness of vision both as regards ends and means. The steward sees his end clearly: he apportions his means to that end, uses as best he may what resources he has. The inference is left as to the wavering vision, both of end and of means, on the part of the children of light. The same thought is in the subsidiary and incidental lesson as to making friends by means of the mammon of unrighteousness. Selfishness, not brotherliness, rules this fraudulent steward, but he sees clearly those facts of our human life, gratitude and kindliness, which make brotherhood possible, and he turns them to his ends. On the other hand, brotherhood is the faith of the children of light, and yet they greatly neglect this rich field. The parable of the Ten Virgins completes this teaching of the foolishness of a half-hearted faith. It hints the irrevocable loss believers bring upon themselves thereby. Life’s opportunities come unexpectedly—calls to service, possibilities of honour and spiritual enriching—and the half-hearted miss these. Their heart-culture, their spirits’ discipline have been sleeping: and the chances of life pass them by.

The seat of all these follies is the heart ( Mark 7:22). It is not any mere action of the intellect which here comes into condemnation. All these forms of foolishness are a ruining self-deception. The mind is there the servant of the heart whose desires have confused and led it astray.

Richard Glaister.

Vine's Expository Dictionary of OT Words [2]

'Ivveleth ( אִוֶּלֶת , Strong'S #200), “foolishness; stupidity.” This noun appears 25 times in the Old Testament. It can mean “foolishness” in the sense of violating God’s law, or “sin” (Ps. 38:5). The word also describes the activities and life-style of the man who ignores the instructions of wisdom (Prov. 5:23). In another nuance, the noun means “thoughtless.” Hence 'ivveleth describes the way a young person is prone to act (Prov. 22:15) and the way any fool or stupid person chatters (Prov. 15:2). Nebâlâh ( נְבָלָה , Strong'S #5039), “foolishness; senselessness; impropriety; stupidity.” This abstract noun appears 13 times in the Old Testament. Its use in 1 Sam. 25:25 signifies “disregarding God’s will.” Nebâlâh is most often used as a word for a serious sin (Gen. 34:7—the first occurrence).

King James Dictionary [3]


1. Folly want of understanding. 2. Foolish practice want of wisdom or good judgment. 3. In a scriptural sense, absurdity folly.

The preaching of the cross is to them that perish foolishness.  1 Corinthians 1 .

Webster's Dictionary [4]

(1): ( n.) The quality of being foolish.

(2): ( n.) A foolish practice; an absurdity.