'Foolish' in the Bible

And the king made a song of grief for Abner and said, Was the death of Abner to be like the death of a foolish man?

And when the ark of the Lord came into the town of David, Michal, Saul's daughter, looking out of the window, saw King David dancing and jumping before the Lord; and to her mind he seemed foolish.

But when David returned to bless his household, Michal the daughter of Saul came out to meet David and said, “How the king of Israel distinguished himself today! He uncovered himself today in the eyes of his servants’ maids as one of the foolish ones shamelessly uncovers himself!”

"No, my brother!" she kept telling him. "Don't humiliate me like this! This just isn't done in Israel! Don't do this utterly foolish thing!

and David declared, saying, 'Ahithophel is among the conspirators with Absalom;' and David saith, 'Make foolish, I pray Thee, the counsel of Ahithophel, O Jehovah.'

David’s conscience troubled him after he had taken a census of the troops. He said to the Lord, “I have sinned greatly in what I’ve done. Now, Lord, because I’ve been very foolish, please take away Your servant’s guilt.”