adv. [f. prec. + -LY2.] In an authoritative way or manner, with authority exercised or possessed; on due or good authority.

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1621.  Bp. Mountagu, Diatribæ, 119. They haue had [to do with tithes] … but not either primarily, or authoritatiuely.

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1647.  Power of Keys, ii. 6. Authoritatively he gave him the keyes.

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1808.  Bentham, Sc. Ref., 7. An authoritatively reported example.

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1855.  Milman, Lat. Chr. (1864), V. IX. viii. 452, note. The Council of Lateran … first authoritatively proclaimed transubstantiation.

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1860.  Froude, Hist. Eng., V. xxiv. 36. Entitled to speak authoritatively.

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