1. Descriptive of being deceitful or pretending to feel one way and actually being the opposite in speech or behavior: "The young man's excessive attention to the elderly woman at the party was recognized by her son as nothing more than a duplicitous way to steal her valuable necklace."
2. A dishonest action that is meant to trick someone or others: "The investigator exposed the financial investor's duplicitous techniques to get people to buy stock in his company."