D defs.my
Entry 2 senses Webster, 1913

Indubious

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