Meaning of “certainty” - Learner’s Dictionary

certainty

noun uk us /ˈsɜːtənti/
FEELING [ U ]

B2 the feeling of being completely sure about something:

I can't say with any certainty what time she left.
SURE THING [ C ]

something that is very likely to happen or cannot be doubted:

There are no absolute certainties in life.

(Definition of “certainty” from the Cambridge Learner’s Dictionary © Cambridge University Press)