E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
means the cursed mouthful. It was a piece of bread consecrated for exorcism, and given to a person to swallow as a test of his guilt. The words of consecration were, May this morsel cause convulsions and find no passage if the accused is guilty, but turn to wholesome nourishment if he is innocent. (Saxon, corse, curse; snd, mouthful.) (See CHOKE.)