What is "brynhildr"

Brynhildr (also spelled Brunhild, Brünnhilde, Brynhild) is a shieldmaiden and a valkyrie in Germanic mythology, where she appears as a main character in the Völsunga saga and some Eddic poems treating the same events. Under the name Brünnhilde she appears in the Nibelungenlied and therefore also in Richard Wagner's opera cycle Der Ring des Nibelungen. She may be inspired by the Visigothic princess Brunhilda of Austrasia. The history of Brynhildr includes fratricide, a long battle between brothers, and dealings with the Huns. She is also known as Sigrdrífa, as written in the poem Sigrdrífumál.