cer‧tain‧ty plural certainties
the state of being completely certain
She knew with absolute certainty that he'd say no.
The result is impossible to predict with any degree of certainty.
the fact that something is certain to happen
certainty of (doing) something
the certainty of being caught
There's no certainty that he'll remember.
something that is definitely true or that will definitely happen:
He usually does quite well, but it's not a certainty.
The only certainty is that there will need to be major changes.