How does the Bible define foolishness?

How does the Bible define foolishness?
God’s Response: Only fools say in their hearts, “There is no God.” Psalms 14:1
Fear of the Lord is the beginning of knowledge. Only fools despise wisdom and discipline. Proverbs 1:7
A wise woman builds her house; a foolish woman tears hers down with her own hands. Proverbs 14:1
Fools have no interest in understanding; they only want to air their own opinions. Proverbs 18:2

The Bible describes fools as having one or more of the following characteristics:
1.     Refusing to acknowledge the existence of a loving God
2.     Making no attempt to develop wisdom and self-discipline
3.     Being entertained by making fun of what is good and moral
4.     Speaking carelessly and thoughtlessly about others
5.     Thinking they are always right