Isostrain is a term used to describe the state of a material or structure that experiences no change in its internal strain under varying external loads. There are several synonyms that can be used instead of isostrain, including isostress, isometrism, and isomechanics. Isostress implies that the external loads applied to the material or structure are distributed equally throughout its surface, resulting in a balanced stress-state. Isometrism is a term used to describe the property of a material or structure that maintains its shape and size under varying external loads. Isomechanics refers to the study of the mechanics of materials that exhibit isostrain or isostress behavior.