Also see definition of "Defy" in Word Study
Defy
DEFY [isbe]
DEFY - de-fi' (charaph, za`am): In 1 Sam 17:10,25,26,36,45 (the story of David and Goliath) and kindred passages, this word is used in its most familiar sense--"to taunt," "challenge to combat" (Hebrew charaph). In Nu 23:7,8 "denounce" would be a better translation than "defy" (Hebrew za`am).
Also see definition of "Defy" in Word Study