Esquivalience is a ghost word that was used in the first and second editions of the New Oxford American Dictionary (NOAD). 'Ghost words' are fake words that are included in a dictionary to entrap plagiarists. However, on the 2001 release of the second edition it was suspiciously 'leaked' that the NOAD had a ghost word somewhere in the E's, and the resulting hunt and particularly the eventual capture of this ghost word resulted in a fair amount of press for the dictionary... at least by the standards of the lexicographer community.
1. "The willful avoidance of one’s official responsibilities; the shirking of duties."2 "lack of interest or motivation".
As it happens, esquivalience did indeed appear in at least one derivative dictionary, making it an effective ghost word: Dictionary.com listed it, citing Webster’s New Millennium Dictionary as the source. This has since been removed. It also appeared in Google Dictionary, which licensed the OED. Google Dictionary has since been taken down in its entirety, but you can still find esquivalience using Google's 'define' feature (i.e., define:esquivalience).
The tale of esquivalience's uncovering has been told and retold in both wordnerd circles and in the popular media (well, Boing Boing and The New Yorker, along with a good handful of viral mills), but essentially dictionary-fanatic Henry Alford spearheaded the search by comparing the NOAD's E section (just 3,128 words) to a less thorough dictionary, and came up with a list of six possibilities (earth loop, EGD, electrofish, ELSS, esquivalience and eurocreep); he ran these by nine respected lexicographers, and six of them agreed that esquivalience was the odd one out. NOAD's editor-in-chief, Erin McKean, confirmed that this was the ghost word, and the world sighed a breath of relief.