'Understanding' in the Bible

For it is written, I will destroy the wisdom of the wise, and set aside the understanding of the understanding ones.

For if I pray with a tongue, my spirit prays, but my understanding is unfruitful.

What is it then? I will pray with the spirit, but I will pray also with the understanding; I will sing with the spirit, but I will sing also with the understanding.

but in the assembly I desire to speak five words with my understanding, that I may instruct others also, rather than ten thousand words in a tongue.