in ‧ du ‧ bi ‧ ta ‧ bly /ɪnˈdjuːbətəbli, ɪnˈdjuːbɪtəbli $ ɪnˈduː-/ BrE AmE adverb formal
[ Word Family: adjective : ↑ doubtful , doubtless, ↑ indubitable , ↑ undoubted ; adverb : ↑ doubtfully , ↑ indubitably , ↑ undoubtedly ; noun : ↑ doubt , ↑ doubter ; verb : ↑ doubt ]
certainly or without doubt:
Mr Sachs is indubitably charming.
—indubitable adjective