'Certain' in the Bible

Now there was a certain man from Ramathaim-zophim from the hill country of Ephraim, and his name was Elkanah the son of Jeroham, the son of Elihu, the son of Tohu, the son of Zuph, an Ephraimite.

But certain worthless men said, “How can this one deliver us?” And they despised him and did not bring him any present. But he kept silent.

David said to Ahimelech the priest, “The king has commissioned me with a matter and has said to me, ‘Let no one know anything about the matter on which I am sending you and with which I have commissioned you; and I have directed the young men to a certain place.’

Then David said, “O Lord God of Israel, Your servant has heard for certain that Saul is seeking to come to Keilah to destroy the city on my account.