proditoriously

Adverb

 * 1)  In a proditorious manner; treacherously, traitorously.
 * , Folio Society, 2006, vol.1, p.221:
 * he humbly calleth for mercy, alleaging that he had justly murthered the murtherer of his father, whom his good chance was to finde there, averring by good witnesses, before them all, that in the Citie of the Leontines, his father had been proditoriously slaine by him, on whom he had now revenged himselfe.