Wyvern folklore is rarely fire-breathing like the four-legged dragon. Sometimes modern fantasy book and media authors have wyverns that are frost-breathing or poison-breathing instead of fire-breathing. The current spelling "wyvern" is not attested before the seventeenth century as "winged two-footed dragon". According to the Oxford English Dictionary, it is an alteration of Middle English "wyver" (attested thirteenth century), from Anglo-French "wivre" (cf. French "guivre" and "vouivre"), which originate from Latin "vīpera", meaning "viper", "adder", or "asp". Conversely, medievalist William Sayers proposes a more complex origin for the term. He notes that the Anglo-French "guivre" and its Middle English derivative ceased to
Tincture (heraldry) not regard it as a "real heraldic tincture". On the whole, French heraldry is known for its use of azure and or, while English heraldry is characterized by heavy use of gules and argent, and unlike French heraldry, it has always made regular use of vert, and occasional, if not extensive, use of purpure. German heraldry is known for its extensive use of or and sable. German and Nordic heraldry rarely make use of purpure or ermine, except in mantling, pavilions, and the lining of crowns and caps. In fact, furs occur infrequently in German and Nordic heraldry. The colours