A previously non-existent word used by a simpleton with poor command of the English language in an attempt to impress. Typically followed by a bogus definition provided by the simpleton in an attempt to legitimize the artword.
Art said that Carl has liberal "underleanings". A search of Websters and a google search turned up no references to the word "underleanings" leading one to believe that it was just another artword. Art's subsequent bogus definition (see artdefinition) confirmed it.