indubitably
Word family (noun) doubt doubter (adjective) doubtful doubtless indubitable undoubted (verb) doubt (adverb) doubtfully indubitably undoubtedly
From Longman Dictionary of Contemporary Englishindubitablyin‧du‧bi‧ta‧bly /ɪnˈdjuːbətəbli $ ɪnˈduː-/ adverb formal TRUEcertainly or without doubt Mr Sachs is indubitably charming. —indubitable adjective