from first and third person singular of Old English durran "to brave danger, dare; venture, presume," from Proto-Germanic *ders- (cf. Old Norse dearr, Old High German giturran, Gothic gadaursan), from PIE *dhers- "to dare, be courageous" (cf. Sanskrit dadharsha "to be bold;" Old Persian darš- "to dare;" Greek thrasys "bold;" Old Church Slavonic druzate "to be bold, dare;" Lithuanian dristi "to dare," drasus "courageous").
An Old English irregular preterite-present verb: darr, dearst, dear were first, second and third person singular present indicative; mostly regularized 16c., though past tense dorste survived as durst, but is now dying, persisting mainly in northern English dialect. Meaning "to challenge or defy (someone)" is first recorded 1570s.