1) Deceitful 2) False 3) Lying 4) Untrue 5) Untruthful 1) French word used in English 2) Given to lying 3) Intentionally untrue 4) Lying 5) Untruthful 
• (a.) Given to deception or falsehood; lying; as, a mendacious person. • (a.) False; counterfeit; containing falsehood; as, a mendacious statement.
Men·da'cious adjective [ Latin mendax , -acis , lying, confer mentiri to lie.] 1. Given to deception or falsehood; lying; as, a mendacious person. 2. False; counterfeit; containing falsehood; as, a mendacious statement. -- 
[adj] - intentionally untrue
mendacious Not truthful, lying or false; such as a mendacious story.
adjective intentionally untrue; `a mendacious statement`
[SAT terms] intentionally untrue given to lying