Define the term "over-processing" in hair treatment.

Over-processing refers specifically to the damage that occurs when chemical treatments, such as hair dye, perms, or relaxers, are applied too often or in excessive amounts without allowing the hair to recover. These chemical processes alter the hair's natural structure, and frequent application can lead to a significant breakdown of the hair's integrity, resulting in brittleness, dryness, and a lack of elasticity. This condition often manifests as split ends, excessive frizz, and an overall unhealthy appearance.

In contrast, the other options describe different types of hair damage but do not accurately capture the concept of over-processing. Damage from styling tools pertains to heat-related harm, while under-processing indicates that the desired chemical effect was not fully achieved. Damage from inadequate conditioning refers to the lack of moisture and nourishment, which is also important but not directly related to the frequency or intensity of chemical applications. Thus, the characterization of over-processing as damage from applying chemical treatments too frequently is crucial to understanding the balance required in hair care practices.