Definition of "fantast"

He is indeed all this; and what he has more than all this peculiar to himself, I seem to convey to my own mind in some measure by saying, — that he is a quiet and sublime enthusiast with a strong tinge of the fantast, — the humourist constantly mingling with, and flashing across, the philosopher, as the darting colours in shot silk play upon the main dye.

1804, Samuel Taylor Coleridge, notes on Thomas Browne's Vulgar Errors

I recall one particularly heady Outreach meeting, in 1985, at which one of the speakers was a fantast named Jack Wheeler, who liked to say that Izvestia had described him as an “ideological gangster” […] .

1987, Joan Didion, Miami, Granta, published 2005, page 190