Certainty

1. Knowledge that is validated or empirically confirmed as, for example, by experiment, by repeated observation, by the attestation of others (in law, by witnesses or evidence constituting proof).

2. A condition of knowledge regarding something in which uncertainty is ignored (whether it is immeasurably small or undetectable, or whether it is considered statistically insignificant) or unperceived.

3. Confidence in the correctness of an evaluation of the probability that a particular event (or activity, state, form, structure, etc) will or will not eventuate.