Adverb
of a certainty (not comparable)
(dated) Without a doubt; certainly.
Know thou of a certainty that every letter revealed in the Bayán is solely intended to evoke submission unto Him Whom God shall make manifest, for it is He Who hath revealed the Bayán prior to His Own manifestation. Báb
But such a thing as that is not known: with such a toy as a guide, the mariner would wreck his ship, of a certainty!, This is a proof that Earth is not a globe." Source: Internet
But then, when Christ was brought to him bound, Pilate sent Him to Herod, giving command to enquire of him, that he might know of a certainty what he should desire concerning Him; making Christ a convenient occasion of reconciliation with the king." Source: Internet