All 3 Uses

perpetual
in
The Gunslinger
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Faint and far, nothing but a tiny dot (it might have been one of those motes that dance perpetually in front of the eyes, except for its constancy), the gunslinger beheld the man in black, moving up the slopes with deadly progress, a minuscule fly on a huge granite wall.†
Chpt 2
Even on the hardscrabble below, where they had toiled and fought for every foot in the killer sun, they had been able to hear the sound of crickets rubbing their legs seductively together in the perpetual green of willow groves above them.†
Chpt 3
Far away, through the gash that led the way into the mountains, he heard the thick mouth of the perpetual thunder.†
Chpt 3 *

Definitions:

(1) (perpetual)
continuing forever without change; or occurring so frequently it seems constant
(2) (meaning too rare to warrant focus)