certainty
cer-tain-ty
noun
The state of being completely sure or having no doubt about something.
"There was no certainty about the outcome."
noun
Something that is definitely going to happen or is undeniably true.
"Death and taxes are certainties."
Thesaurus
Synonyms: foregone conclusion, sure thing
Antonyms: doubt, doubtfulness, dubiety, dubiousness, incertitude, precariousness, uncertainness, uncertainty