His victory in the election is 'almost a certainty'. [=it is nearly certain/definite that he will win the election]
It is difficult to say 'with certainty' [=in a certain or definite way] which of the plays was written first.
Scientists still do not know with any degree of 'certainty' why the disease spread so quickly.
(..) But we must march. Yeah! - We must stand up. - Yeah! We must make a massive demonstration of our moral certainty. I'm so glad we're here together today. I thank you for standing up. For we shall be victorious in our quest. We shall cross the finish line hand in hand. (..)2014 Selma