noun

• (uncountable) The fact or condition of being untruthful; dishonesty.
  "Mendacity is not a uniform offence: it changes its colour according to the nature and substance of the offence to which it is rendered or endeavoured to be rendered subservient. Mendacity, employed in drawing down upon an innocent head the destroying sword of justice, is murder: murder, encompassed with all its correspondent terror. Mendacity, employed in the obtainment of money, is but depredation. Yet, while predatory mendacity is punished with death, the punishment for the murderous mendacity is in comparison but a flea-bite."
• (countable) A deceit, falsehood, or lie.
  "The scandalous bronze-lacker age, of hungry animalisms, spiritual impotencies and mendacities, will have to run its course, till the Pit swallow it."