v.tr. (-ies, -ied) 1 resist openly; refuse to obey. 2 (of a thing) present insuperable obstacles to (defies solution). 3 (foll. by to + infin.) challenge (a person) to do or prove something. 4 archaic challenge to combat.
[ ME f. OF defier f. Rmc (as DIS-, L fidus faithful) ]