Answer:
Hard to catch, easy to hold. Can't be seen, unless it's cold
White bird, featherless, flying out of paradise. Flying over sea and land. Dying in my hand.
What word has kst in the middle, in the beginning, and at the end?
I am seen in the water. If seen in the sky, I am in the rainbow, a jay's feather, and lapis lazuli.
I can move even when you are still. I can be one or many.
You use it between your head and your toes, the more it works the thinner it grows.