1. the state of being unsure of something

(synonym) doubt , uncertainty , incertitude , dubiety , doubtfulness

(hypernym) cognitive state , state of mind

(hyponym) mental reservation , reservation , arriere pensee

2. uncertainty about the truth or factuality of existence of something; "the dubiousness of his claim"; "there is no question about the validity of the enterprise"

(synonym) doubt , doubtfulness , question

(hypernym) uncertainty , uncertainness