habitually lying or untruthful


US English

UK English

Part of speech



Lying, deceptive, untruthful, fraudulent, dishonest, untrustworthy


Honest, truthful, trustworthy, credible, sincere

Example sentences

  • The witness’s mendacious testimony was discredited when the truth was revealed.
  • The mendacious advertisement made false claims about the product’s benefits.
  • The politician was caught in a mendacious scandal, and was forced to resign.


Mendacious refers to someone or something that is lying or deceptive. The term is often used to describe people who deliberately tell falsehoods or make false statements with the intention of misleading others. Mendacious statements or actions can be used to gain an advantage, to conceal the truth, or to manipulate others. Mendacious behavior is considered unethical and is often punished in various ways, such as fines, imprisonment, or social ostracism. In general, mendacious people or things are seen as untrustworthy or dishonest, and are often the subject of suspicion or contempt. The term can also be used to describe a system or culture that is based on lies and deception, such as a corrupt government or a fraudulent business