(suggested, of course, by idiotism)

the worthless word for the day is: idioticon

[fr. Gk idiotikos] /id e OT ikon/
a dictionary of a dialect

"Idioticon, a word of frequent use in Germany, signifying a dictionary confined to a particular dialect, or containing words and phrases peculiar to one part of a country."
- William Brande, A dictionary of science, literature and art [1842]

"The novel's [De Verteller (The Narrator)] subtitle is 'Idioticon voor zegelbewaarders' [Idioticon for Guardians of the Seals], a reference to a dictionary of a certain idiom (with the association: idiocy)."
- Anthony Mertens, Postmodern Elements in... Dutch Fiction [2005]