fraudulent (adj.)youdaoicibaDictYouDict[fraudulent 词源字典]
early 15c., from Old French fraudulent, from Latin fraudulentus "cheating, deceitful, dishonest," from stem of fraus "deceit" (see fraud). Earlier was fraudful (c. 1400). The Old French word was fraudios. Related: Fraudulently.[fraudulent etymology, fraudulent origin, 英语词源]