Hair Glossary – Function of Beauty

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Hair Glossary

From how your hair behaves to the patterns you style every day, this glossary breaks down the terms that actually matter so you can understand your hair with confidence.

Hair Term	Definition
Hair Type	Hair type refers to your hair’s natural pattern. It’s influenced by the shape of the hair follicle, which determines whether hair grows straight, wavy, curly or coily. There are four main hair types: straight (type 1), wavy (type 2), curly (type 3), and coily (type 4).
Hair Texture	Hair texture describes how your hair feels to the touch. It can feel smooth, coarse, silky, or rough depending on strand thickness and cuticle health.
Hair Density	Hair density is how many individual strands you have on your scalp. It's usually fullest at the crown and can change over time due to factors like genetics, hormones, nutrition, and age.
Porosity	Porosity is how easily your hair takes in and holds onto moisture. It’s based on how open your cuticle layer is and usually falls into 3 categories: low, medium, or high. Low porosity: Cuticles are tightly closed, so moisture has a harder time getting in. High porosity: Cuticles are more open, letting moisture in fast but not holding onto it as well.
Hair Elasticity	Hair elasticity is how well your hair can stretch and bounce back. When elasticity is strong, hair holds it shape better, with more body, movement, and curl definition.
Hair Cuticle	The cuticle is the outer layer of your hair strand. Its overlapping cells act like a protective shield, helping guard the inner layers from damage.
Sebum	Sebum is your scalp's natural oil. It helps keep the scalp moisturized and protected while supporting a healthy scalp environment. Sebum levels can change over time, often influenced by hormones.
Moisture Retention	Moisture retention is your hair's ability to keep moisture locked in after it's been hydrated. When retention is strong, hair stays softer, smoother, and more comfortable between washes.

Styling & Pattern Term	Definition
Frizz	Frizz is when hair lifts or puffs instead of staying smooth or defined. It can look different depending on the cause, like surface frizz from humidity, halo frizz at the crown, or frizz that comes from dryness.
Definition	Definition is how clearly your waves, curls, or coils show their natural shape instead of looking loose or undefined.
Clumping	Clumping is when individual strands naturally group together, creating more defintion waves or curls.
Shrinkage	Shrinkage is when hair looks much shorter once it dries. It happens most often when curls and coils and is a natural result of elastic hair.
Flat Roots	Flat roots happen when hair sits close to the scalp with little lift. They're often caused by oil at the roots, fine hair, or products that feel too heavy.
Volume Drop (Loss of Lift)	Volume drop is when hair starts out full, then slowly falls flat as the day goes on. Oil at the roots or heavy products are usually the cause.
Curl Memory	Curl memory is how easily curls snap back to their natural shape after styling or stretching.
Breaking the Cast	Breaking the cast is the step after styling when hair is completely dry and you gently scrunch to get rid of the crunchy feeling. It keeps definition while bring back softness and movement.