BLAZON, a heraldic shield, a coat of arms properly "described" according to the rules of heraldry, hence a proper heraldic description of such a coat. The O. Fr. blason seems originally to have meant simply a shield as a means of defence and not a shield-shaped surface for the display of armorial bearings, but this is difficult to reconcile with the generally accepted derivation from the Ger. blasen, to blow, proclaim, English "blaze," to noise abroad, to declare. In the 16th century the heraldic term, and "blaze" and "blazon" in the sense of proclaim, had much influence on each other.
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)