touch. 1  to touch a person or thing. 2  to be or come in contact. 3  to come near to something; verge (on or upon) 4  to pertain; bear (on or upon) 5  to treat a topic slightly or in passing: with on or upon. 6  to stop briefly or land (at a port, etc.) during a voyage. 7  Geom. to be tangent.