Nonthought. An expression from Zen Buddhism that refers to a state of mind in which one acts without thinking, without emotions, feelings or ego consciousness. Experienced martial artists act like this during a fight. In this state the mind work very fast and without hesitation, as it is without intention or goal.

What is mushin?
Mushin: nonthought. D. T. Suzuki wrote at length on mushin. It’s  nonthought, unconsciously, Mind without Thought, non-thought. It is the essence of Zen. Supposing you do something or want something in your ordinary life: if you act consciously, you are not mushin. If the impulse is expressed at conscious thought, it is not Zen. That is why training in a practice that involves the muscles an whole body is so important. It’s important for speaking too, Most people speak after the brain has given them the order to do so. But if you become mushin, hishiryo, you can speak unconsciously, without thought.Take a mondo*: if you ask a professor a question he has to think before he answers. But the zen monk answers without thinking, unconsciously. That’s why a Zen mondo is important.
It’s the the same with actions. The brain thinks and you act afterwards. That is not mushin. Mushin is the body thinking. If you understand that, you can understand Zen. Most Zen stories have to do with mushin. Wisdom and intellectual learning are not the same. in everyday life, in conversations, most people think first and then answer; but very intelligent people use wisdom and do not think. They speak and answer through intuition. Book learning is different from true knowledge. In time, one ceases using the brain to answer questions.
Through zazen you can understand how one can speak unconsciously. Your superficial brain rests and your inner brain becomes active and receives energy. In a mondo my answers come from the inner brain; the activity begins there. My inner brain answers you unconsciously, mushin. That’s why a zen mondo is different from an oral examination at the university. Speaking out of one’s book-learning is not wisdom. From long practice of zazen you will acquire this unconsciously: wisdom, not book-learning.
When I give a talk, for example, I must prepare what I am going to say. Learning first… and a bit of wisdom. But the moment I stand up in the hall I begin to talk unconsciously and I don’t always stick to what I have prepared. I look at at the faces and see whether I need to change my talk. There is no more plan, my words come out of the unconscious, an that is why they impress people so strongly. That is teisho. Deshimaru 1991, 77