'Foolish' in the Bible

Then Samuel said to Saul, "You have made a foolish choice! You have not obeyed the commandment that the Lord your God gave you. Had you done that, the Lord would have established your kingdom over Israel forever!

My lord should not pay attention to this wicked man Nabal. He simply lives up to his name! His name means 'fool,' and he is indeed foolish! But I, your servant, did not see the servants my lord sent.