Gobbledygook is the standard spelling of the noun originally meaning language characterized by jargon or pretentious verbiage. The secondary spelling gobbledegook appears about once for every three instances of gobbledygook—although, somewhat interestingly, gobbledegook is preferred in British English and especially rare in American English.
Gobbledygook is American in origin, with the first recorded instances appearing in the middle 1940s.1 Its original meaning has been somewhat eroded. Although that sense remains in use, the word is sometimes used to mean simply nonsense (not necessarily jargon or pretentious verbiage).
In its original definition, gobbledygook is synonymous with jargon, doubletalk, and verbiage, as in these instances:
This may sound like theoretical gobbledygook, but it has real implications for what happens next. [Campus Progress]
But what he really needed was an app that could translate the patent gobbledegook contained in that Lodsys document. [BBC News]
The white paper is so riddled with meaningless, fuzzy gobbledygook on what China’s evolving legal system is that one can only wonder what the intention of publishing it was. [Atlantic]
But in recent usage, the word often means nonsense without necessarily implying jargon or pretention—for example:
But are these birds really a few pumpkins shy of a pie, or is it all just a bunch of gobbledygook? [San Jose Mercury News]
I would review this review in one word: Gobbledygook. The movie is amazing. [comment on New York Times]
1. http://www.oed.com/view/Entry/79601 ^