Definition of "fantastically"

"The Chengtu revolutionaries were fantastically colourful in the Szechwanese manner—they costumed themselves as heroes of the stage and their energies were chiefly occupied in tying ropes across the main streets so that when Imperial officials rode by in their litters they would have to get down and crawl under, losing face.

1942 March, “Notes and News: Monument to a Stillborn Railway”, in Railway Magazine, page 88

The provinces of Liaoning, Heilongjiang and Jilin are fantastically cold in winter, indeed one of the major tourist attractions for the hardy is the display of ice-carved figures in public parks (especially in Haerbin, Heilongjiang province). The long winters have average temperatures between — 20°C and — 27°C, although the short summers are hot.

1988, Frances Wood, “Town and Countryside”, in A Companion to China‎, 1st U.S. edition, New York: St. Martin's Press, page 35

One must be especially careful when using Google to determine frequency as there is a very real risk of fantastically overestimating the frequency and subsequent importance of a term.

2018, James Lambert, “A multitude of ‘lishes’: The nomenclature of hybridity”, in English World-Wide‎, page 15