Other forms: defied, defying, defies
To defy is to openly refuse to obey a greater power. Defy an order, defy the ban, defied his father.
The openness is the point: defying is refusing where everybody can see. It also means to resist being explained or done: defy description, defy belief, defy gravity, defy the odds — and those are among the commonest uses. Note defiance, the noun; defiant, which describes the manner; and that defy takes a direct object with no preposition, which catches out speakers of several other languages.
1verbdefyTo openly refuse to obey a greater power.
“Thousands of protesters defied the government's ban and marched through the capital.”
2verbresistTo resist being explained or done.
“The whole arrangement defies description.”
defy is an open refusal.
The Latin is to take back your faith. A knight who defied his lord took his faith back from him and stood against him; to defy anything is still to look it in the eye and refuse.
hooks ontofaith
Old French desfier meant to renounce one's allegiance — literally to un-faith somebody, from Latin fides, faith. Defying somebody was originally breaking a bond rather than disobeying an order.
Proto-Indo-European
*bʰeydʰ-
Latin
dis- — away
Vulgar Latin
*disfidare — renounce one's faith
Old French
desfier
English, today
defy
Built from
From Old French desfier, from Vulgar Latin disfidare (“renounce one's faith”), from Latin dis- (“away”) + fidus (“faithful”). Meaning shifted in the 14th century from "be disloyal" to "challenge". Contrast confide, fidelity, faith.
Etymology from Wiktionary, CC BY-SA