How is 'frizz' defined in relation to hair?

Frizz is defined as hair that appears dry and lacks smoothness. This characteristic occurs when the hair cuticle becomes raised, allowing moisture from the environment to enter the hair shaft. When hair absorbs moisture, it can swell, leading to an uneven surface that causes strands to lift away from one another, resulting in a frizzy appearance. This is particularly common in naturally curly or wavy hair types, where the texture can be more prone to frizz due to the shape of the hair strands and their tendency to retain moisture.

In contrast, hair that appears oily and heavy lacks the texture that defines frizz, while excess shine usually indicates healthy, well-moisturized hair rather than dryness. Overly styled hair might be defined by its look or holding products used, but does not specifically relate to the dryness and rough texture that characterize frizz. Thus, the definition of frizz focuses on the lack of smoothness and the dry appearance of the hair.