/dahrnd/ , Informal.
adj.
1. irritating; damned; confounded: Get that darned bicycle out of the driveway!
adv.
2. very; extremely; remarkably: She's a darned good tennis player.
[ 1800-10; euphemism for DAMNED, perh. by construing dern dark, dreary (now obs.) as an intensifier in phrases such as dern and dreary, dern and doleful ]