An example of to defy is to break a law by going on land that is posted with a no trespassing sign.
An act that defies explanation; a problem that defies any conventional approach.
She defied her accusers to prove their charges.
The puzzle defied solution.
Origin of defy
- Middle English defien from Old French desfier from Vulgar Latin disfīdāre Latin dis- dis- Latin fīdus faithful bheidh- in Indo-European roots
From American Heritage Dictionary of the English Language, 5th Edition
- From Old French desfier, from Vulgar Latin *disfidare (“renounce one's faith”), from Latin dis- (“away”) + fidus (“faithful”). Meaning shifted 14c. from "be disloyal" to "challenge."