the state of being uncertain; doubt; hesitancy

His uncertainty gave impetus to his inquiry.

an instance of uncertainty, doubt, etc.

unpredictability; indeterminacy; indefiniteness.

noun

certainty , definiteness , security , sureness

noun

ambiguity , ambivalence , anxiety , bewilderment , concern , confusion , conjecture , contingency , dilemma , disquiet , distrust , doubtfulness , dubiety , guesswork , hesitancy , hesitation , incertitude , inconclusiveness , indecision , irresolution , lack of confidence , misgiving , mistrust , mystification , oscillation , perplexity , puzzle , puzzlement , qualm , quandary , query , questionableness , reserve , scruple , skepticism , suspicion , trouble , uneasiness , unpredictability , vagueness , wonder , worry , ambiguousness , cloudiness , equivocalness , indefiniteness , nebulousness , obscureness , obscurity , unclearness , dubiousness , question , capriciousness , doubt , fallibility , fortuity , gamble , inconstancy , risk , suspense , variableness