'Certain' in the Bible

A certain man lived in Ramathaim-zophim, which is in the hill country of Ephraim. He was Jeroham's son Elkanah, the grandson of Elihu and grandson of Tohu, who was the son of Zuph, an Ephraimite.

David told Ahimelech the priest, "The king commanded me about a matter, saying to me, "Don't let anyone know anything about the matter I'm sending you to do and about which I've commanded you. I've directed the young men to a certain place.'

Now I know for certain that you will be king, and that the kingdom will be established under your authority.

David sent out spies and found out for certain that Saul had arrived.