mendacious

[men-dey-shuhs]
adjective
  1. telling lies, especially habitually; dishonest; lying; untruthful: a mendacious person.
  2. false or untrue: a mendacious report.

Origin of mendacious

1610–20; < Latin mendāci- (see mendacity) + -ous
Related formsmen·da·cious·ly, adverbmen·da·cious·ness, nounun·men·da·cious, adjectiveun·men·da·cious·ly, adverb

Antonyms for mendacious

1, 2. veracious.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Word Origin and History for mendaciousness

mendacious

adj.

1610s, from Middle French mendacieux, from Latin mendacium "a lie, untruth, falsehood, fiction," from mendax (genitive mendacis) "lying, deceitful," from menda "fault, defect, carelessness in writing," from PIE root *mend- "physical defect, fault" (see amend (v.)). The sense evolution of Latin mendax was influenced by mentiri "to speak falsely, lie, deceive." Related: Mendaciously; mendaciousness.

Online Etymology Dictionary, © 2010 Douglas Harper