Endurance Limit:
The endurance limit, also known as the fatigue strength, is the maximum stress level that a material can withstand for an infinite number of cycles without experiencing fatigue failure. It is an important property for materials that are subjected to cyclic loading or repeated stress over time. If a material has a high endurance limit, it means it can withstand a large number of stress cycles without failing.

Ultimate Tensile Strength:
Ultimate tensile strength (UTS) is the maximum stress level a material can withstand before it fails in tension. It represents the maximum amount of tensile stress the material can handle without breaking. UTS is an important property as it indicates the material's ability to resist being pulled apart or stretched.

Elastic Modulus:
The elastic modulus, also known as Young's modulus, is a measure of a material's stiffness or rigidity. It quantifies the relationship between stress and strain in a material when it is subjected to an external force. A higher elastic modulus indicates a stiffer material that requires a larger force to deform it. It is an essential property in structural design and material selection.

Yield Stress:
Yield stress, also known as yield strength, is the stress level at which a material begins to deform permanently or plastically. It is the point at which the material transitions from elastic deformation to plastic deformation. Yield stress is crucial in determining the safe operating limit of a material and plays a significant role in design calculations.

Explanation:
The property that is not exactly a property of a material among the given options is the endurance limit (option A). The endurance limit is a specific property related to the fatigue behavior of a material. It represents the stress level below which the material can endure an infinite number of stress cycles without failing due to fatigue. However, not all materials exhibit an endurance limit.

Some materials, such as steel, aluminum, and titanium alloys, exhibit an endurance limit, while others, like cast iron and copper alloys, do not have a well-defined endurance limit. For materials without an endurance limit, the fatigue strength is determined by the stress level at a specific number of cycles, usually expressed as the stress-life curve or S-N curve.

In summary, while endurance limit is an important property for materials susceptible to fatigue failure, it is not a universal property applicable to all materials. The other properties listed (ultimate tensile strength, elastic modulus, and yield stress) are fundamental properties that are commonly used to characterize the mechanical behavior of materials.