I understand why a person would have cosmetic surgery for some serious disfigurement.
The power of resisting displacement constitutes stability, the power of each piece to resist disfigurement is its stiffness; and its power to resist breaking, its strength.
Disfigurement does not occur although hearing and visual problems are typical.
In young trees, galling caused by wooly aphids can cause serious disfigurement.
The condition of stiffness is that the strain or disfigurement shall not be greater than is consistent with the purposes of the structure; and the condition of strength is that the stress shall be within the limits of that which the material can bear with safety against breaking.