Cortex hair definition, as a noun phrase, defines the innermost layer of a hair strand composed of elongated, keratinized cells. This layer contributes to hair's strength, elasticity, and color. For instance, a person with thick hair has a larger cortex diameter than someone with fine hair.
Understanding cortex hair definition is crucial for hair care. The cortex determines hair's texture, porosity, and response to chemical treatments. Historically, scientists have studied the cortex to develop hair care products that target specific hair concerns.