Definition of "wyvern"

The jargon of heraldry, its griffins, its moldwarps, its wyverns, and its dragons.

1814 July 7, [Walter Scott], Waverley; […], volumes (please specify |volume=I to III), Edinburgh: […] James Ballantyne and Co. for Archibald Constable and Co.; London: Longman, Hurst, Rees, Orme, and Brown

Notions of freedom are tied up in drink / Our ideal life contains a tavern / Where man may sit and talk of or just think / All without fear of the nighted wyvern, / Or yet another tavern where it appears.

1940-54 The Collected Poetry of Malcolm Lowry, "WE SIT UNHACKLED DRUNK AND MAD TO EDIT", UBC Press,1992, p.222