From late 17th century French effronterie, from effronté (“shameless, insolent”), from Old French esfronté, from Vulgar Latin *exfrontātus. Compare Latin effrōns (“barefaced”), from the prefix ex- (“from”) + frōns (“forehead”) (English: front).
effrontery (countable and uncountable, plural effronteries)
- (uncountable) Insolent and shameless audacity.
- (countable) An act of insolent and shameless audacity.