Factoid is a word coined by Norman Mailer for "an item of unreliable information that is repeated so often that it becomes accepted as fact". http://en.wikipedia.org/wiki/Factoid
In QA literature it is often used in the "unverified fact" sense (which is also mentioned in Wikipedia article).
The Wikipedia article says it well:
A factoid is a questionable or spurious (unverified, false, or fabricated) statement presented as a fact, but without supporting evidence, although the term can have conflicting meanings.
The Wikipedia article says it well:
A factoid is a questionable or spurious (unverified, false, or fabricated) statement presented as a fact, but without supporting evidence, although the term can have conflicting meanings.