untruthfulun‧truth‧ful /ʌnˈtruːθfəl/ adjective 
 
- In this, of course, the untruthful organization is totally mistaken.
 - Most of what they do and others do to them is illegal, deceitful and untruthful.
 - Much better to be untruthful and leave Laura thinking that but for a migraine, they might have spent the night together.
 
  adverbtrulytruthfully ≠ untruthfullytruenountruth ≠ untruthtruthfulnessadjectivetrue ≠ untruetruthful ≠ untruthful