Mendacious means in the habit of lying. A mendacious account, mendacious claims, thoroughly mendacious.
It is the formal accusation of lying, which is why it appears in courts and in parliaments where calling somebody a liar is not allowed. It describes a habit rather than one false statement.
1adjectivemendaciousIn the habit of lying.
“The mendacious salesman told us the car had never been in an accident.”
mendacious is a quality.
Latin mendax means lying, from mendum, a fault.
Proto-Indo-European
*men-
Latin
mendācium — lie, untruth
Middle French
mendacieux
English, today
mendacious
Built from
Borrowed from Middle French mendacieux, from Latin mendācium (“lie, untruth”), from mendāx (“lying”), + -ious.
Etymology from Wiktionary, CC BY-SA