"doubtfulness" in the noun sense
1. doubt, uncertainty, incertitude, dubiety, doubtfulness, dubiousness
the state of being unsure of something
2. doubt, dubiousness, doubtfulness, question
uncertainty about the truth or factuality or existence of something
"the dubiousness of his claim"
"there is no question about the validity of the enterprise"
Source: WordNet® (An amazing lexical database of English)
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