Restoring force acting per unit area…is called STRESS

Stress consists of bodily changes produced by physiological or psychological conditions that tend to upset the homestatic balance. In medical language stress is defined as a perturbation of the bodies homeostasis.

Stress is force by area
Stress is similar to Strain. For Example : I strains my ear ? to listen carefully that what my elders are saying because I am ? taking these days a lot of stress.
Stress is defined as internal porperty of material which resist external loading
Force/Area

Feeling of anxiety and nervousness