Wiktionary
n. 1 (context idiomatic UK Ireland English) gall, shamelessness, cheek. 2 (context idiomatic UK Ireland English) A person with gall.
Usage examples of "brass neck".
Julia working a subtle PR ploy, or Royan crowning their achievement with a typical brass neck gesture?
He had contacts at the highest level all over Europe, a prodigious memory, a brass neck, and great ingenuity (some said lack of scruple) which together raised him to a unique position in his profession.
Simon, still running on balls and brass neck, was about to parrot it out automatically when he remembered that he was just a marketing exec playing at being a hitman, and it was the marketing exec's name and address on the mobile bills.
We found a couple of seats on the aisle and, as we settled in,I wondered why he'd decided to put me on the spot like this I've got a certain amount of chutzpah but I didn't have the brass neck to sit through this particular movie in the company of Jesus without feeling uncomfortable.