untruthful
— Adjective
– English
~ not expressing or given to expressing the truth; "the statement given under oath was untruthful"; "an untruthful person"
untruthfully
— Adverb
– English
~ in a mendacious and untruthful manner; "I told him, quite untruthfully, that I had just returned from leave"
untruthfulness
— Noun
– English
~ the quality of being untruthful