As nouns the difference between untruth and untruthfulness
is that untruth is a lie or falsehood while untruthfulness is (uncountable) the state of being untruthful; dishonesty.
untruth
English
Noun
(
en noun)
A lie or falsehood.
The condition of being false; truthlessness.
Synonyms
* see
untruthfulness
English
Noun
(es)
(uncountable) The state of being untruthful; dishonesty.
(countable) Something which is untrue; untruth.