ghost word - an accidental word form never in
established usage; especially: one arising from an
editorial or typographical error or a mistaken
pronunciation (as phantomnation or dord)

*Webster's New International Dict., 2nd ed.

the worthless word for the day is: mountweazel

[see quotes]
a bogus entry purposely inserted into a reference
work: a copyright trap

"Turn to page 1,850 of the 1975 edition of the New
Columbia Encyclopedia and you'll find an entry for
Lillian Virginia Mountweazel, a fountain designer
turned photographer.. she never existed."
- Henry Alford, The New Yorker Aug. 29, 2005

"And only publishing insiders know that a Mountweazel
is "a bogus entry purposely inserted in a dictionary
or encyclopedia as a means of protecting copyright.""
- William Safire, N.Y. Times Mag. Dec 3, 2006