A braggart or boastful person; someone who talks big or exaggerates about their accomplishments.
From the character Captain Bobadil in Ben Jonson's play 'Every Man in His Humour' (1598), a archetypal blowhard. The character's name became a common noun meaning 'boastful person.'
This is how literary characters become common words! Captain Bobadil was so famous for his empty boasting that people started calling real braggarts 'bobadils.' It happened with 'Quixotic' (from Cervantes), 'Machiavellian' (from Machiavelli), and 'Bowdlerize' (from Thomas Bowdler).
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