Pronunciation: (bang'kō, bäng'-), [key]
—n., pl. -cos,
a declaration made by a bettor in certain gambling games, as baccarat and chemin de fer, indicating a bet matching the full amount in the bank, to the exclusion of all previous lower bets: often used as an interjection.
to make such a declaration.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.