Entry 2 senses Webster, 1913 Indubious /ĭdˌ-o͞ob'-ē-əs/ · In·du·bi·ous · IPA /ɪnˈdjuːbiəs/ 01 a. Not dubious or doubtful; certain. 1. Not dubious or doubtful; certain. 2. Not doubting; unsuspecting.