The Collaborative International Dictionary
Indubious
Indubious \In*du"bi*ous\, a. [L. indubius. See In- not, and Dubious.]
Not dubious or doubtful; certain.
Not doubting; unsuspecting. ``Indubious confidence.''
--Harvey.
Wiktionary
indubious
a. 1 Not dubious or doubtful; certain. 2 Not doubting; unsuspecting.