NIHILARTIKEL/ˈnʌɪhɪlˌærtiːkl/
A deliberately erroneous entry in a dictionary or other reference book.
If you have a copy of the New Oxford American Dictionary, please disregard the entry for esquivalience, supposedly the wilful avoidance of one’s official responsibilities or the shirking of duties. It has been discovered to be a fake entry. Compilers of reference works often include them to reveal copyright infringements by competitors. Map makers might include a fictitious location, for example, or the compilers of wine encyclopaedias add entries for non-existent beverages (such as that for Via Gra in one of Robert Parker's recent wine guides). The 1980 edition of the New Grove Dictionary of Music included a spoof entry for the composer Esrum-Hellerup. Since nobody consulting such works would ever have cause to look them up, they do no harm (unless you’re one of that rare breed that reads such works cover to cover and commits the whole to memory).
Because we have no English word for the concept, some English writers have used what looks like a German word, Nihilartikel, for such deliberately invalid entries. This is formed from Latin nihil, nothing, plus German Artikel, so “nothing article”. There's some doubt whether this is a genuine German word, or one formed in English as a joke and unknowingly copied.
Others have used Mountweazel, which derives from the false entry for Lillian Virginia Mountweazel that appeared in the 1975 edition of the New Columbia Encyclopedia. (The article claimed that she was a fountain designer turned photographer, celebrated for a collection of photographs of rural American mailboxes titled “Flags Up!”) A much older example of a Nihilartikel (or just possibly a skittish jest) formed the final entry in several editions of Rupert Hughes’ The Music Lovers’ Encyclopedia, first published in 1903; it asserted that zzxjoanw was the name of a Maori drum. I know at least two popular works on etymology that cite the word in all seriousness, despite the fact that there’s no Z, X or J in the Maori language and that it was exposed as a fake in 1976.
Another term sometimes employed is ghost word, though this strictly refers to one which appears in a dictionary through an editorial or printer’s error, such as the entry for dord in Webster’s New International Dictionary in 1934, a misprint for D or d, as an abbreviation for “density”.
