Zanshin is a Japanese word which means positive completion and follow through. An action that is done with unity of body and mind that creates a lingering spirit (an affect that carries on).
It is also used to describe a quality expressed in various arts. It has the feeling of stillness of action at the end of the action and the holding of the moment. For example after swinging the sword, the practitioner holds the sword still for a moment and lets the stillness set in. After giving shiatsu pressure rather than quickly moving to the next point you let your mind gather in stillness at the point you are pressuring.
Another word related to Zanshin is Ishin. Zanshin naturally occurs after an action performed with Ishin – unity of Body, Mind and Spirit or oneness of self. When our actions are centered and grounded and we are absorbed in that action, there is a positive ambience that is created on completion of the action. This is the 2nd meaning of Zanshin - lingering spirit. In the bigger view, it is living our fullest and deepest life. Then after leaving this world, there is a positive lingering influence – A Zanshin.