Dictionary the definition can be given as follows:
safety: 1.
2.
the quality or condition of being safe; freedom from danger, injury, or damage; security.
(technical) the stability of a building, machine or other construction, the tranquillity of its operation and the fact that it does not endanger its environment. Safety is always relative; it can be only defined if the condition of its surrounding is defined as well. It only exists if the object/construction is not bearing force.