The elastic limit of a material is defined as:

The elastic limit of a material is defined as the maximum stress that it can withstand without undergoing permanent deformation. When a material is subjected to stress, it can deform elastically up to a certain point. Once this elastic limit is exceeded, the material will no longer return to its original shape when the load is removed, resulting in permanent changes to its structure. This point is crucial in material science and engineering because it helps determine the operational boundaries for safe use in various applications.

For understanding, the other options refer to different aspects of material behavior. The second choice relates to the failure point of a material, which indicates complete fracture or rupture, beyond which the material cannot function as intended. The third choice describes the ultimate tensile strength and relates to the maximum stress before breaking but doesn't specify the behavior upon load removal. The fourth choice refers to the yield point, which is slightly different, as it marks the onset of plastic deformation but does not necessarily indicate where permanent deformation starts. Understanding the elastic limit is vital for engineers in ensuring structural integrity and safety in their designs.