Toughening is a word that refers to the process of making something stronger or more resilient. There are several synonyms that can be used to describe this process, including fortifying, strengthening, hardening, and solidifying. Fortifying typically refers to the addition of substances that enhance the nutritional or structural quality of something, while strengthening implies an increase in physical strength or endurance. Hardening and solidifying both suggest the development of a more durable, rigid structure, with hardening typically involving a chemical or thermal process, and solidifying referring to the transformation of a liquid or semi-solid substance into a solid state. Regardless of the specific term used, the goal of any type of toughening is to create a more resilient and enduring end product.