'Despair' in the Bible

And David said in his heart, I shall now perish one day by the hand of Saul: there is nothing better for me than that I should speedily escape into the land of the Philistines; and Saul shall despair of me, to seek me any more in any coast of Israel: so shall I escape out of his hand.

Therefore I went about to cause my heart to despair of all the labour which I took under the sun.

We are troubled on every side, yet not distressed; we are perplexed, but not in despair;