The Complete Guide to Hair Terminology

Here is a comprehensive guide to hair terminology, broken down into categories for easy understanding.

1. Hair Anatomy & Structure

These terms describe the physical makeup of the hair strand itself.

• Cuticle: The outermost layer of the hair shaft. It consists of overlapping, scale-like cells that protect the inner layers. “Raised” cuticles lead to frizz and damage; smooth, closed cuticles create shine.
• Cortex: The middle and thickest layer of the hair shaft. It contains melanin (which gives hair its color), proteins, and bonds. This layer determines the hair’s strength, elasticity, and texture.
• Medulla: The innermost, soft, central core of the hair. It is not always present, especially in fine or light-colored hair.
• Hair Follicle: The living part of the hair located under the scalp. It’s the root from which the hair grows.
• Sebaceous Gland: A gland attached to the hair follicle that produces sebum (natural oil), which conditions the hair and scalp.
• Hydrophilic / Hydrophobic:
  • Hydrophilic: “Water-loving.” Hair that is hydrophilic is porous and absorbs moisture easily.
  • Hydrophobic: “Water-fearing.” Healthy, virgin hair is naturally hydrophobic, repelling water initially.

2. Hair Characteristics & Texture

Terms used to describe the natural state of hair.

• Porosity: The hair’s ability to absorb and retain moisture.
  • Low Porosity: Cuticles are tight and closed. Hair resists water, is prone to product buildup, and takes a long time to dry.
  • Medium/Normal Porosity: Cuticles are slightly open. Hair holds moisture well, processes color predictably, and looks healthy.
  • High Porosity: Cuticles are lifted or missing. Hair absorbs water instantly but loses it just as fast; it is prone to frizz and breakage.
• Elasticity: The ability of the hair to stretch and return to its original length without breaking. (Healthy hair can stretch up to 50% of its length when wet). Low elasticity results in brittle hair that snaps easily.
• Density: The number of individual hair strands on the head (fine, medium, or coarse density—not to be confused with strand thickness).
• Strand Thickness: The width of a single hair strand.
  • Fine: Thin diameter, easily breakable, can look limp.
  • Medium: The most common texture.
  • Coarse: Large diameter, strong, can be resistant to chemical treatments.
• Hair Typing System (Andre Walker/Loosely): A system used to classify curl patterns.
  • Type 1: Straight (no curl).
  • Type 2: Wavy (S-shaped waves).
  • Type 3: Curly (defined loops or spirals).
  • Type 4: Coily/Kinky (tight zig-zags or z-shaped curls).

3. Chemical Services & Processing

Terms related to coloring, relaxing, and perming.

• Virgin Hair: Hair that has never been chemically treated (colored, permed, relaxed) or processed.
• Base Color: The natural underlying pigment of the hair.
• Level: The system used to measure the darkness or lightness of hair color, typically on a scale of 1 (black) to 10 (lightest blonde).
• Tone: The warmth or coolness of a color (e.g., ash, gold, copper, violet).
• Developer (Oxidizing Agent): Hydrogen peroxide used with hair color to open the cuticle and activate the color molecules. Volumes (10, 20, 30, 40) indicate strength.
• Lightening (Decolorization): The process of removing natural or artificial pigment from the hair.
• Bleach (Lightener): A chemical used to lighten hair by breaking down melanin.
• Relaxer: A chemical treatment used to permanently straighten curly or coily hair by breaking disulfide bonds.
• Perm (Permanent Wave): A chemical treatment used to add curl or wave to straight hair.
• Disulfide Bonds: Strong chemical bonds within the cortex that give hair its strength and shape. These are broken and reformed during chemical services (perms, relaxers, straightening).
• Hydrogen Bonds: Weak, temporary bonds broken by water (wet setting) or heat (heat styling).

4. Damage & Condition

Terms describing the health and state of the hair.

• Split Ends (Trichoptilosis): The fraying or splitting of the hair shaft at the tip.
• Bubble Hair: A specific type of heat damage where moisture inside the hair shaft boils, creating bubbles in the cortex, leading to sudden breakage.
• Hygral Fatigue: Damage caused by repeated swelling and drying of the hair shaft (over-washing or over-moisturizing), leading to weak, mushy, or limp hair.
• Mechanical Damage: Breakage caused by physical stress (rough brushing, tight hairstyles, friction from towels).
• Protein Overload: A condition where hair has too much protein and not enough moisture, resulting in stiff, brittle, or straw-like hair that breaks easily.
• Over-Moisturized: Hair that has absorbed too much water or moisturizing products, becoming gummy, limp, and lacking structure.

5. Cutting & Styling Techniques

Common terms used in salons and styling.

• Point Cutting: A texturizing technique where scissors are used vertically to cut into the ends of the hair, removing bulk and creating softness.
• Blunt Cut: A straight-across cut with no layers, creating a heavy, full look at the ends.
• Layering: Cutting hair at different lengths to create movement, volume, and shape.
• Graduation (Stack): A cutting technique where hair is cut at increasing lengths to create a stacked or angled look (common in bobs).
• Razor Cutting: Using a straight razor to cut hair, creating soft, wispy ends (not recommended for curly hair as it can cause frizz).
• Sectioning: Dividing the hair into manageable parts for cutting, coloring, or styling.
• Slippage: A term used in braiding or twisting to describe the technique of adding hair (extensions) by sliding it along the natural hair strand rather than adding it at the root.

6. Protective Styling & Natural Hair

Terms common in the curly, coily, and natural hair communities.

• Protective Style: A hairstyle that tucks the ends of the hair away to protect them from environmental damage and manipulation (e.g., braids, twists, wigs, buns).
• Low Manipulation Style: A style that requires minimal touching, combing, or styling to reduce breakage.
• Wash-and-Go: A style where curly or coily hair is washed, conditioned, and styled with product, then allowed to air-dry or diffuse-dry without further manipulation.
• Shrinkage: The phenomenon where curly or coily hair appears significantly shorter than its actual length when dry due to the curl pattern tightening.
• Co-wash (Conditioner Wash): Washing the hair with conditioner (usually a cleansing conditioner) instead of shampoo to avoid stripping natural oils.
• Slip: The slick, lubricating quality of a conditioner that allows a comb or fingers to glide through the hair easily without snagging.
• Cast (Gel Cast): The hard, crunchy layer left on hair after applying a strong-hold gel. This is often “scrunched out” (SOTC) to reveal soft, defined curls that last for days.
• Scalp Detox: A deep cleansing treatment to remove buildup (sebum, product residue, hard water minerals) from the scalp.

7. Tools & Accessories

• Paddle Brush: A large, flat, wide brush used for detangling long, straight hair and smoothing.
• Denman Brush: A styling brush with rows of nylon pins, widely used in the curly community to define curl clumps.
• Diffuser: An attachment for a hair dryer that disperses air flow, used to dry curly hair without disturbing the curl pattern or causing frizz.
• Hot Comb (Press Comb): A metal comb that is heated to temporarily straighten curly or coily hair.
• Boar Bristle Brush: A brush made from boar hair, used to distribute natural oils (sebum) from the scalp down the hair shaft.
• Clips (Sectioning / Duckbill): Flat, metal clips used to hold sections of hair out of the way during cutting or coloring.