A
AHA (alpha hydroxy acids) — Exfoliants like lactic or glycolic acid.
Amodimethicone — A silicone that bonds to hair, providing long-lasting softness. Less buildup than Dimethicone.
Ammonium Lauryl Sulfate — A strong anionic surfactant. Very cleansing, drying.
B
Behenyl Alcohol / Behentrimonium Methosulfate — Fatty conditioning agents. Great for slip and detangling.
Bond-builder — Product that rebuilds broken disulfide bonds. Olaplex No.3, K18.
C
Cetearyl Alcohol — Fatty alcohol, conditioning. NOT drying.
Ceramide — Lipid that rebuilds the hair's protective barrier.
Chelating — Binds to minerals (iron, calcium) to remove them from hair. Good for hard water.
Clarifying — Deep-cleaning shampoo removing buildup.
CO-wash — Using conditioner as shampoo. For curly/coily hair.
Cuticle — The outermost layer of hair; protective "shingles."
D
Dimethicone — Common silicone, smoothing. Non-soluble version builds up.
Disulfide bonds — The strongest bonds in hair. Broken by bleach and heat.
E
Elasticity — Hair's ability to stretch and return. A marker of health.
Emollient — An ingredient that softens (like oil or butter).
F
F-layer / 18-MEA — The thin waxy outer coating on healthy hair.
Fatty alcohol — Conditioning alcohol (Cetyl, Cetearyl, Stearyl). Not drying.
G
Glycerin — Humectant; pulls moisture from air or products.
Glucoside (Decyl, Lauryl, Coco) — Gentle non-ionic surfactants.
H
Humectant — Ingredient that pulls water (glycerin, propylene glycol).
Hydrolyzed protein — Protein broken into smaller pieces so it can penetrate hair.
Hygral fatigue — Weakening from repeated water swelling.
I
INCI — International Nomenclature of Cosmetic Ingredients. The ingredient list.
K
Keratin — The main protein in hair.
Ketoconazole — Antifungal ingredient for dandruff/SD.
L
LOC/LCO method — Liquid-Oil-Cream or Liquid-Cream-Oil layering for moisture.
Low porosity — Cuticle is closed; resists moisture absorption.
M
Malassezia — A yeast that causes seborrheic dermatitis.
MI/MCI (Methylisothiazolinone) — Preservative. Banned in EU leave-on products.
N
Niacinamide — Vitamin B3. Strengthens skin barrier.
Non-ionic — Mild class of surfactants (glucosides).
O
Olaplex — Bond-builder brand; specifically rebuilds disulfide bonds.
Omega-3 — Fatty acid that supports scalp health.
P
Panthenol / Pro-Vitamin B5 — Humectant, soothing, strengthens hair.
PEG — Polyethylene glycol. Makes non-soluble ingredients water-soluble.
pH — Acidity level. Hair works best at 4.5–5.5.
Piroctone olamine — Gentle antifungal; alternative to zinc pyrithione.
Porosity — How much water hair absorbs.
Q
Quaternium-15 — Formaldehyde-releasing preservative. Avoid.
R
Relaxer — Chemical that permanently straightens hair by breaking disulfide bonds.
S
Sebum — Natural oil from scalp sebaceous glands.
Seborrheic dermatitis — Inflammatory skin condition causing yellow, greasy flakes.
SLS (Sodium Lauryl Sulfate) — Harsh anionic surfactant.
SLES (Sodium Laureth Sulfate) — Milder than SLS.
Squalane — Stable light oil, similar to natural sebum.
Surfactant — Cleansing agent (shampoo).
T
Telogen effluvium — Temporary shedding after stressor, illness, childbirth.
Traction alopecia — Hair loss from constant tension.
U
UV filter — Sunscreen ingredients for hair products.
Z
Zinc pyrithione — Antifungal in many dandruff shampoos.
Still unfamiliar?
The Mutaly quiz explains what each recommendation means in plain language, so you don't need to memorize any of this.