"Truthiness" is a word coined by comedian Stephen Colbert; it
describes something that is felt in the gut or in the heart to be
true, but not necessarily borne out by fact or logic. Even though
the word "truthiness" was an archaic form of the word "truth,"
found in the Oxford English Dictionary and The Century Dictionary,
since it was not used in the way that Colbert used it, it is
considered a new word.
The word caught on quickly and in 2005 the American Dialect
Society named truthiness its word of the year. Merriam-Webster
named it the word of the year and entered it in its dictionary in
2006.