de·fy / diˈfī/ • v. (-fies, -fied) [tr.] openly resist or refuse to obey. ∎  (of a thing) make (an action or quality) almost impossible: his actions defy belief. ∎  [tr.] appear to be challenging (someone) to do or prove something: he glowered at her, defying her to mock him.DERIVATIVES: de·fi·er n.

defy †renounce allegiance to; (arch.) challenge to a contest; challenge the power of, set at nought. XIV. — (O)F. défier :- Rom. *disfīdāre, f. L. dis-, DE- 6 + fīdus trustful, rel. to fidēs FAITH. Cf. DEFIANCE.