Sentence:  Here in the cool darkness Mr. Podger could still feel the warmth of midday , could still see the yellow butterflies <WSD>dancing</WSD> over the road , could still see the friendly grin on the young , sun-browned face as the driver looked back over his shoulder for a moment before the car streaked out of sight . 
Meaning of the word marked with <WSD> tags:  move in a graceful and rhythmical way