The athlete has honed their skill to such a keen sense that every muscle in their body is attuned to accomplish their goal.
In bowling, this term is more often used with regard to your arm swing, foot work, and release of the bowling ball.
Whenever I tell my students to try something new, their comment is always, "that feels strange."
When I hear that, my immediate reply is "okay, we won't move on to another point until you feel completely comfortable with this new thing you're trying."
There is nothing to be gained by moving on to something else if they are not feeling good about their form, approach, arm swing, or rhythm.
The biggest part of practicing and becoming consistent is getting to the point in your game where you don't have to think about what you are doing.
You're totally comfortable and are only focusing on your target instead of having three or four things about your form getting in your way.
There is a "thing" that many good bowlers have which I've labeled as, "foul line correction."
Here's the gist of it: as the ball is released, the bowler's unconscious mind senses that something doesn't feel right and makes an automatic correction of his/her release to set the ball on the lane in the proper strike line.
Watch the pros on TV and you'll see such things as an arm being thrown out to the right, a ball being released with very little lift, or the wrist snapping harder than usual.
Watch some of your local high average bowlers and chances are, you'll see the same sort of things happening with their releases.
"Foul line correction" could also be thought of as, "instinct."
When an athlete is "in the zone," everything seems to go his/her way and there is nothing they can do wrong.
I suspect that all of us have felt that way at one time or another.
It doesn't necessarily have to be associated with sports either.
Have you ever been at work and completed a task only to have something "tell" you that you did it wrong?
Have you ever thought of a problem and something "told" you what the answer was?
Have you ever started to do something and "thought better" of it?
Chances are, you were so tuned in to the task, problem, or objective, that your body and/or mind sensed the correct manner in which it should be done and "automatically" knew what you had to do.
We all perform better if we are comfortable.
Practicing and being knowledgeable (aware) of our bowling senses are the keys to getting there.
From this time going forward, add this thought to your purpose for practice sessions:
"My objective is to fine-tune my bowling so that I am instinctively performing greatly and my mind/body is attuned to the 'foul-line correction' needed to perform at this high level."
If you've been bowling for a while and have put in a fair amount of practice, I believe that you have the "instinctive" feeling already in you; it just needs to be developed further.