telling lies, especially habitually; dishonest; lying; untruthful: a mendacious person.
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. Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for mendacious

Contemporary Examples of mendacious

Historical Examples of mendacious

  • Party journalism in the Province of Quebec is peculiarly bitter and mendacious.

  • Bein' a woman, you're too feeble-witted for reason, too mendacious for trooth.'

    Faro Nell and Her Friends

    Alfred Henry Lewis

  • With this mendacious explanation Gustavus was forced to be content.

  • The mendacious fiction was framed by the chief priests and elders of the people.

    Jesus the Christ

    James Edward Talmage

  • Angie said suddenly and turned with a mendacious inspiration on her brother.

    The Fifth Ace

    Douglas Grant

Word Origin and History for mendacious

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