Men·dac'i·ty noun ; plural Mendacities . [ Latin mendacitas .] 1. The quality or state of being mendacious; a habit of lying. Macaulay. 2. A falsehood; a lie. Sir T. Browne. Syn. -- Lying; deceit; untruth; falsehood. Found on http://www.encyclo.co.uk/webster/M/46