Uncertainty or doubt.
Uncertainty.
Apposite is a word, but you probably mean opposite. The opposite of doubt is certainty. Doubt and certainty are antonyms.
Uncertainty or doubt.
Some opposite words for certainty include disbelief, doubt, and distrust.
uncertainity.
The opposite of doubt is certainty. The opposite of a doubt about a person could be trust.
It is with a great deal of certainty that I offer this example.
belief, certainty, confidence, dependence, faith, reliance, trust
Comperio
This is doubtful, or dubious; yet the opposite is a certainty.
Certainty.
Sentence:He tried to base the certainty of mathematics on that of direct observation and induction.