2. Adverb. Darn; damned; extremely. ¹
3. Interjection. (US informal) Euphemism for darn, in itself a euphemism for damn. ¹
4. Verb. (slang) Rhotized pronunciation of doing. ¹
¹ Source: wiktionary.com
Definition of Durn
1. to damn [v -ED, -ING, -S] - See also: damn