For as its belt sparkled and glittered now in one part and now in another, and what was light one instant, at another time was dark, so the figure itself fluctuated in its distinctness: being now a thing with one arm, now with one leg, now with twenty legs, now a pair of legs without a head, now a head without a body: of which dissolving parts, no outline would be visible in the dense gloom wherein they melted away.
There are no more uses of "fluctuate" in the book.
Show samples from other sources
Cattle markets tend to fluctuate a lot, and some years, you don’t make much of anything.
Nicholas Sparks -- The Longest Ride
My courage and my resolution is firm; but my hopes fluctuate, and my spirits are often depressed.