'Understand' in the Bible

Now we are writing nothing to you other than what you can read and also understand. I hope you will understand completely—

just as you also partially did understand us, that we are your reason to be proud as you also are ours, in the day of our Lord Jesus.

For we do not dare to classify or to compare ourselves with some who commend themselves, but [they] themselves, [when they] measure themselves by themselves and compare themselves with themselves, do not understand.