What is the definition of Tension?

Tension (physics): may be described as a pulling force transmitted axially, or an action-reaction pair of forces acting at each end of a structure. For example, muscular tension is the result of contractile proteins attempting to pull a muscle to a shorter length while being resisted by joints, connective tissue and external loads. Often this may be visualized as a "stretching" or "lengthening" force resulting in "tautness". The rope in a game of tug-of-war is a good example.