Noun

1. A verbal or written description of a coat of arms.
   • 1894, James Parker, A Glossary of Terms Used in Heraldry:

     ...it should never be forgotten that the best blazon is that which is the most perspicuous

2. A formalized language for describing a coat of arms.
   • 1997, Gerard J. Brault, Early Blazon:

     We must banish, therefore, the persistent but wholly erroneous notion that the heralds invented many of the terms used in blazon and borrowed the rest from the everyday lexicon of terms...

3. : A coat of arms or a banner depicting a coat of arms.

Verb

1. To describe a coat of arms.
   • 1889, Charles Norton Elvin, A Dictionary of Heraldry

     After Blazoning the Shield, you proceed to the exterior ornaments viz.: The Helmet, Lambrequin, Crest, Supporters, Badge, and Motto