the quality of seeming to be true according to one's intuition, opinion, or perception without regard to logic, factual evidence, or the like: the growing trend of truthiness as opposed to truth.
2.
Rare. truthfulness or faithfulness.
Origin: 1824 for def. 2;2005 for def. 1 (coined by Stephen Colbert (1964– ), U.S. comedian and TV host); truth + -y1 + -ness