fnord

Etymology
A neologism from the Principia Discordia popularized in the Illuminatus! trilogy.

Noun

 * 1)  A metasyntactic variable, similar to foo and bar.

Interjection

 * 1)  A word (which may or may not be "fnord" itself) commonly held to be invisible to the conscious mind, but subliminally causing a sense of unease or sudden anger when encountered. So used in the Illuminatus! trilogy.
 * 2)  A word defined as having no definition.