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Webster 1913 Edition

adv.

Boastfully; with boasting.

“He boastingly tells you.”

Burke.

adv.

In an ostentatious manner; with boasting.

boastingly ‎(comparative more boastingly, superlative most boastingly)

Boastfully.
- 1603, John Florio, translating Michel de Montaigne, Essayes, London: Edward Blount, OCLC 946730821, II.7:
  I doe not thinke that any Spartane Citizen did boastingly glorifie himselfe for his valor, because it was a popular vertue in that Nation […].