THIS is taken from gotquestions.com
Question: “What is a fool according to the book of Proverbs?”
Answer: The word fool appears forty times in the ESV version of Proverbs. The ways of the fool are often contrasted with the ways of the wise. In modern usage a “fool” can be a “dupe,” an “ignoramus,” or just a “ridiculous person,” but how is a “fool” defined in Proverbs?
A look at some of the occurrences of the word fool in Proverbs helps provide an explanation. Proverbs 10:8 refers to a “babbling fool.” One trait of a fool is that he is a constant talker who is not known for listening to wisdom (see also 10:10).
Proverbs 10:14 states, “The mouth of a fool brings ruin near.” This contrasts the speech of the fool with the knowledge of the wise. A fool does not care about learning. He’s too busy talking.
Proverbs 10:18 teaches, “Whoever utters slander is a fool.” The fool will speak poorly of other people rather than be known as an encourager.
Proverbs 10:23 adds that “doing wrong is like a joke to a fool.” A foolish person does not take sin or its consequences seriously.
Proverbs 12:15 says, “The way of a fool is right in his own eyes, but a wise man listens to advice.” The fool rejects the advice of others and instead listens only to himself.
Proverbs 13:16 notes, “A fool flaunts his folly.” In other words, a foolish person is proud of his wrong actions.
Proverbs 14:16 teaches that “a fool is reckless and careless.” A fool does not plan ahead but rather lives life without considering the impact his actions have on himself and others.
Proverbs 15:5 shows that “a fool despises his father’s instruction.” The foolish person will not listen to his parents or obey them. In fact, he spurns what his father says.
Proverbs 26:11 uses emblematic parallelism to graphically illustrate the behavior of fools: “As a dog returns to its vomit, so fools repeat their folly.” A fool is known for repeating mistakes rather than learning from past wrongs.
Often in Scripture, a fool is associated with wickedness and a direct denial of God (e.g., in Psalm 53:1). Because God has infinite wisdom, the person who neglects God will naturally miss out on wisdom—he will become a fool. A fool is anyone who does not follow the warnings and commands of God. A fool lacks wisdom, has no concern for others, does not desire to avoid sin, and brags about his sinful actions. The Scripture is clear we are to avoid living as a fool; rather, we are to fear the Lord, walk in His wisdom, and follow His ways. We know that “those who walk in wisdom are kept safe” (Proverbs 28:26).