Definition: the quality of stating facts that you believe or want to be true, rather than stating facts that are known to be true.
Famous catchphrase from the hilarious Stephen Colbert: this piece was designed for Stephen and he wrote to say that it hangs proudly in his office at The Colbert Report!
Our version of "Truthiness" was mentioned in this article in New York magazine:
At about 3:30 on the day of the first taping, during a rehearsal, Colbert stopped and beckoned to his writers. He'd decided they needed a better word. "It's not stupid enough," he said. "We're not talking about truth, we're talking about something that seems like truth--the truth we want to exist." Then he had an idea: "Truthiness." He now displays, on a bookshelf in his office, a sampler embroidered with TRUTHINESS inside a gold frame.