What is the term for hair that has been chemically treated to change its structure?

The term for hair that has been chemically treated to change its structure is "permanent wave or relaxer." This classification encompasses processes that alter the natural structure of the hair, resulting in either curls or waves through a permanent wave or straightening via a relaxer.

When hair is treated with chemicals to create a permanent wave, the disulfide bonds in the hair are broken down and then reformed, resulting in a new texture that maintains its shape long after the treatment is applied. Similarly, relaxers work by chemically altering the protein structure of the hair, allowing it to become straight and remain that way until the hair grows out or is cut.

Other options, such as color-treated hair, specifically refer to changes in hair color without necessarily altering its structure. Bleached hair refers to hair that has had its pigment removed, changing its color but not fundamentally altering the hair's structure like a permanent wave or relaxer does. Texturized hair can involve techniques that add volume or movement to the hair but doesn’t necessarily denote a structural change as defined by chemical treatments. Hence, the correct term accurately reflects the nature of structural change in hair.