A coat of arms or heraldic shield; a heraldic blazon or description of armorial bearings.
From Middle English and Old French 'blason,' related to 'blaze.' The term evolved from the bright, showy nature of displayed coats of arms.
Medieval heralds developed such complex rules for describing shields that 'heraldic language' is practically its own system—a blason could tell you someone's entire family history and social rank!
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