The American Heritage® Dictionary of the English Language: Fourth Edition. 2000.
Appendix I
Indo-European Roots
ENTRY:
dhers-
DEFINITION:
To venture, be bold. O-grade form *dhors- and zero-grade form *dhs-.dare, durst, from Old English dearr and durst, first and third person singular present and past indicative of durran, to venture, respectively from Germanic *dors- and *durs-. (Pokorny dhers- 259.)
s-. dare, durst, from Old English dearr and durst, first and third person singular present and past indicative of durran, to venture, respectively from Germanic *dors- and *durs-. (Pokorny dhers- 259.) 
