1835, jocular formation, perhaps based on fantasy.
There is an indescribable complaint, which will never allow a moment's repose to mind or body; which nothing will satisfy—which allows of no beginning, and no ending—which wheels round the mind like the squirrel in its cage, ever moving, but still making no progress. It is called the Fantods. From the diagnostics, we pronounce Lord Brougham incurably diseased with the Fantods. [The Metropolitan, London, October 1835]