Major — de Coverley straightened with astonishment at Milo’s effrontery and concentrated upon him the full fury of his storming countenance with its rugged overhang of gullied forehead and huge crag of a humpbacked nose that came charging out of his face wrathfully like a Big Ten fullback.
There are no more uses of "effrontery" in the book.
Show samples from other sources
She had the effrontery to laugh at the mayor’s request.
Armed with too much confidence and effrontery, she made a lot of enemies.