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.
(..) He has the power to wipe out the entire human race and If we believe there even a % chance that he is our enemy, we have to take it as an absolute certainty. And we have to destroy him. But, he is not our enemy. Not today. years in Gotham, Alfred. We've seen what promises are worth. (..)2016 Batman v Superman: Dawn of Justice