natural process
natural action
action *****
activity *****

Possessed of a free, natural action, he made the ball come quickly off the pitch.

In the front, the horse should exhibit a natural high action.

He reached into his back pocket, slowly, smoothly, as if it was the most natural action in the world.

Such a very natural action, too, if you come to think of it.

The natural action of a man in pursuing a little boy would be to run after him.

At the time it had been a simple enough thing to do; a natural and spontaneous action.

Some wisdom comes out of every natural and innocent action.

The rest of the team suddenly realized it was a perfectly natural action for someone who expected to be met at the plane.

And there was the natural action of ultraviolet radiation from the sun.

It admits a natural action of the structure group K.