The term 'stiffened' can be used to describe a variety of processes that involve making something more solid or rigid. This can include freezing, jelling, gelling, congealing, tautening, solidifying, condensing, thickening, reinforcing, hardening, tensing, and starching. For example, freezing something can make it stiffer, while jelling and gelling involve the use of gelatin to create a firmer texture. Congealing involves the cooling of a liquid to form a semi-solid mass, while tautening is the process of tightening or stretching something. Solidifying is the process of changing something from a liquid or gas to a solid, while condensing is the process of reducing the volume of a gas or vapor. Thickening is the process of increasing the viscosity of a liquid, while reinforcing is the process of strengthening something with additional material. Hardening is the process of making something harder, while tensing is the process of making something tighter. Starching is the process of treating fabric with a starch solution to make it stiffer. All of these processes can be used to stiffen something, making it more rigid and solid.