Hair Care Glossary
A word you don’t know? Look it up here.
- Anagen
- The growing phase of a hair. On the scalp it can last up to six years or longer, and hair grows about a centimeter a month.
Source: DermNet NZ. - Breakage
- A hair that snapped, with a blunt, split or frayed tip.
- Build-up
- What’s left behind by products and oil. It weighs fine hair down and makes everything feel coated. A clarifying wash lifts it.
- Clarifying
- A deeper wash that lifts build-up. Useful now and then, not every wash.
- Cuticle
- The outer layer of a strand, made of overlapping scales. Lying flat, hair feels smooth. Lifted, it feels rough and tangles.
- Dew point
- A weather number for how much water is in the air. Many weather apps show it. High means humid. Low means dry.
- Ears down
- Our shorthand for where conditioner, leave-ins and oil go: from about ear level to the ends, not at the roots.
- Fine
- The width of each strand. You can barely feel a fine strand between your fingers. Fine hair can still be plenty of hair. More on Fine.
- Keratin
- The protein hair is mostly made of. A salon “keratin treatment” is something else: a smoothing service. Ask what’s in it.
- Medium
- A strand you can feel between your fingers that still feels light and smooth. The middle of the four strand widths.
- Sebum
- The natural oil your scalp makes.
- Slip
- How easily fingers or a comb move through wet hair. More slip, less pulling while you detangle.
- Surfactant
- The part of shampoo that lifts oil so water can rinse it away.
- Thick
- A strand you can feel clearly that still feels smooth. Thick is how wide each hair is, not how much hair you have. More on Thick.
- Wiry
- A strand that feels stiff or rough instead of smooth, and springs back. Wiry has its own answer on the quiz.
Sources: DermNet NZ, Hair loss (hair cycle section; updated May 2023, re-checked 17 Oct 2026) · Gavazzoni Dias MF. International Journal of Trichology 2015;7(1) (checked 17 Oct 2026) · D’Souza P, Rathi SK. Indian Journal of Dermatology 2015;60(3) (checked 17 Oct 2026)
Spot something we got wrong? Tell us and we’ll fix it.