Normal force
FORCE EXERTED ON AN OBJECT BY A BODY WITH WHICH IT IS IN CONTACT, AND VICE VERSA
Normal Force; Normal reaction
In mechanics, the normal force F_n is the component of a contact force that is perpendicular to the surface that an object contacts, as in Figure 1. In this instance normal is used in the geometric sense and means perpendicular, as opposed to the common language use of normal meaning "ordinary" or "expected".