Beauty Glossary

Plain-English definitions of skincare ingredients, makeup techniques, hair care terms, and common beauty terminology. Use the alphabet below to jump to any section.

How to use this glossary

Beauty terms explained simply

Each term is explained in plain English with practical context, including what the term means and how it is commonly used in beauty and personal-care discussions. Use the alphabet navigation to find a specific term quickly.

Common Beauty Terms

Niacinamide: A form of vitamin B3 used in skincare. It is commonly included in formulas designed to support the skin barrier, improve uneven tone, and help manage excess oil.
Retinol: An over-the-counter retinoid derived from vitamin A. It is used in skincare for concerns such as acne, uneven texture, and signs of photoaging.
Broad-Spectrum SPF: A sunscreen labeled broad-spectrum provides protection against both UVA and UVB radiation. SPF primarily describes the level of protection against UVB-related sunburn.
Hyaluronic Acid: A humectant that attracts and helps retain water. It is commonly used in skincare products formulated to increase skin hydration.
Salicylic Acid: A beta hydroxy acid commonly used in skincare. Because it is oil-soluble, it can help loosen material within pores and is often used in products for acne-prone or oily skin.
Ceramide: A type of lipid naturally found in the skin barrier. Ceramides are commonly used in moisturizers and other products designed to support the skin barrier and reduce moisture loss.

A

AHA (Alpha Hydroxy Acids): Water-soluble exfoliating acids used in skincare. Common examples include glycolic acid, lactic acid, and mandelic acid. AHAs help loosen dead skin cells at the surface and can improve the appearance of uneven texture and tone. Skin sensitivity varies by product and concentration. Explore our skincare guides.
Acrylic Nails: A nail enhancement made by combining a liquid monomer with a powder polymer that hardens into a durable material. Acrylic enhancements require maintenance as the natural nail grows and should be removed carefully to avoid unnecessary nail damage. Read our manicure comparison.
Antioxidant: A substance that helps counter oxidative processes involving unstable molecules known as free radicals. In skincare, commonly discussed antioxidants include vitamin C, vitamin E, ferulic acid, and certain plant-derived compounds.
Azelaic Acid: A naturally occurring dicarboxylic acid used in skincare and dermatology. It may be used for concerns including acne, uneven pigmentation, and redness. Available strengths and formulations vary by country and product.

B

BHA (Beta Hydroxy Acid): A class of exfoliating acids. In skincare, the term BHA most commonly refers to salicylic acid. It is oil-soluble and is often used in products formulated for oily or acne-prone skin.
BIAB (Builder In A Bottle): A gel nail product designed to provide additional structure and strength to the natural nail. BIAB products vary by formulation and application method, and they still require appropriate preparation and removal.
Broad-Spectrum SPF: A sunscreen labeled broad-spectrum provides protection against both UVA and UVB radiation. SPF primarily indicates the level of protection against UVB-related sunburn.

C

Ceramide: A type of lipid that naturally forms part of the skin barrier. Ceramides are commonly included in moisturizers and other skincare products designed to support the barrier and reduce moisture loss.
Comedogenic: Describes a substance or formulation that may contribute to the formation of comedones, such as blackheads and whiteheads. Individual responses vary, and the term "non-comedogenic" does not guarantee that a product will be suitable for every acne-prone person.
Curly Girl Method (CGM): A hair-care approach associated with caring for naturally curly or wavy hair while paying particular attention to cleansing, conditioning, styling, and minimizing practices that may interfere with an individual's curl pattern. Approaches vary among people who follow it. Explore our hair-care guides.

D

Dermatologist-Tested: A product label indicating that a dermatologist was involved in some form of product testing or assessment. The phrase alone does not explain the testing method, number of participants, or whether the dermatologist personally recommends the product.
Double Cleansing: A two-step cleansing routine in which one cleanser is used to remove products such as makeup or sunscreen, followed by another cleanser to clean the skin. It may be useful for some people, particularly at the end of the day, but it is not required for every skin type or routine.

E

Eau de Parfum (EDP): A fragrance category that generally contains a higher concentration of fragrance materials than eau de toilette. Exact concentration and longevity vary between brands and formulas, so the terms should not be treated as fixed guarantees of wear time.
Eau de Toilette (EDT): A fragrance category generally lighter in concentration than eau de parfum. The actual concentration, character, and longevity can vary considerably between fragrances and manufacturers.
Emollient: An ingredient that helps soften and smooth the skin by filling spaces between skin cells. Common examples include certain oils, fatty alcohols, esters, and other lipid-based ingredients.
Exfoliation: The process of removing or loosening dead skin cells from the skin's surface. Common approaches include physical exfoliation and chemical exfoliation using ingredients such as AHAs and BHAs. Over-exfoliation can irritate the skin.

F

Fitzpatrick Skin Type: A six-category classification system describing how different skin types tend to respond to ultraviolet exposure, particularly whether they burn or tan. It is used in dermatology and other settings involving assessment of UV response.
Fragrance-Free: A product described as fragrance-free is generally formulated without added fragrance ingredients intended to provide scent. Labeling practices can vary, so checking the full ingredient list can provide additional information. People with sensitive skin may prefer fragrance-free products.

G

Gel Polish: A nail-polish formulation that is cured using UV or LED light. Gel manicures can provide longer wear than conventional nail polish, but proper application and removal are important to minimize damage to the natural nail.
Glycolic Acid: An alpha hydroxy acid with a relatively small molecular structure. It is used in skincare products intended to exfoliate the skin and improve the appearance of uneven texture and tone. Higher concentrations can increase the potential for irritation.

H

Humectant: An ingredient that attracts and helps retain water. Common humectants used in skincare include hyaluronic acid, glycerin, and urea. Humectants are often combined with emollients and occlusives in moisturizing formulas.
Hyaluronic Acid (HA): A naturally occurring substance with strong water-binding properties. In topical skincare, hyaluronic acid is used as a humectant to help increase hydration at the skin's surface.
Hyperpigmentation: An area of skin that appears darker because of increased or uneven pigmentation. It can have several causes, including ultraviolet exposure, inflammation, hormonal changes, and skin injury. Treatment depends on the underlying cause.

I

INCI: International Nomenclature of Cosmetic Ingredients — a standardized naming system used for cosmetic ingredients on product labels in many markets. Reading an ingredient list can help consumers understand which ingredients are included in a formula.

K

Keratin: A structural protein found in hair, nails, and the outermost layer of skin. Hair products marketed as keratin treatments can use different formulations and processes, so their effects and safety considerations vary.

L

Lactic Acid: An alpha hydroxy acid that can exfoliate the skin. It is commonly used in skincare products formulated to improve the appearance of uneven texture and tone. The strength and tolerability depend on the formulation and concentration.

M

Microbiome (Skin): The collection of microorganisms that live on and in the skin. These microorganisms interact with the skin and its surrounding environment. Skin care routines can influence the skin's surface environment, although the relationship between products and the microbiome is complex.
Mineral Sunscreen: A sunscreen that uses mineral UV filters such as zinc oxide and/or titanium dioxide. These filters help protect skin from ultraviolet radiation. Mineral sunscreens are sometimes preferred by people who find certain other sunscreen formulations irritating.

N

Niacinamide (Vitamin B3): A form of vitamin B3 used in skincare products. Research supports several potential cosmetic and dermatological uses, including supporting the skin barrier, improving the appearance of uneven tone, and helping manage excess sebum. Different products use different concentrations and formulations. Explore ingredient comparisons.
Non-Comedogenic: A marketing term used to indicate that a product is formulated with a lower likelihood of clogging pores. It is not a guarantee that a product will never cause breakouts, because individual skin responses vary.

O

Occlusive: An ingredient or product that forms a layer over the skin and helps reduce water loss. Common occlusive ingredients include petrolatum, mineral oil, and certain waxes. Occlusives are often used in moisturizers designed for dry skin.

P

Patch Test: A small-area test used before applying a new skincare product more widely. A product can be applied to a small area of skin according to appropriate testing guidance and monitored for signs of irritation or an allergic reaction. A home patch test cannot guarantee that a product will not cause a reaction elsewhere on the body.
pH (in skincare): A measure of how acidic or alkaline a substance is. The skin has a naturally acidic surface environment, and cleanser formulations can differ in pH. Product performance and skin tolerability depend on the complete formulation rather than pH alone.
Pomade: A hair-styling product used to provide hold, shape, texture, or shine. Pomades differ considerably in formulation, including water-based and oil-based products, so their hold and ease of removal vary.

R

Retinoid: A broad group of vitamin A derivatives used in skincare and dermatology. Retinoids include ingredients such as retinol, retinaldehyde, retinyl esters, and prescription retinoids. Their uses and strengths vary.
Retinol: An over-the-counter retinoid used in skincare for concerns such as uneven texture, pigmentation, acne, and visible signs of photoaging. It can cause irritation when introduced too quickly, so gradual use is commonly recommended. See our ingredient comparisons.

S

Salicylic Acid: A beta hydroxy acid commonly used in skincare. It is oil-soluble and can help loosen dead skin cells and material within pores. It is frequently used in products intended for oily or acne-prone skin.
Slugging: A skincare practice in which an occlusive product, commonly petrolatum, is applied as the final step of a nighttime routine to reduce water loss. It may be useful for some people with dry skin, while others may find heavy occlusive products uncomfortable or unsuitable.
SPF (Sun Protection Factor): A measure used to describe the level of protection a sunscreen provides primarily against UVB radiation. Higher SPF values provide greater protection under standardized testing conditions, while real-world protection also depends on applying enough sunscreen and reapplying when appropriate.
Squalane: A lightweight emollient commonly used in skincare to soften the skin and reduce moisture loss. Squalane is a stable form of squalene and can be derived from plant-based sources or other sources depending on the product.

T

Toner: A skincare product traditionally applied after cleansing. Modern toners can have different purposes, including hydration, soothing, or delivering specific ingredients. Whether a toner is useful depends on the formulation and the rest of the skincare routine.
Tretinoin: A prescription retinoid containing tretinoin, a form of vitamin A. It is used in dermatology for conditions including acne and photoaging. It can cause irritation, dryness, peeling, and increased sensitivity, particularly when treatment begins.
Trichologist: A person who specializes in hair and scalp concerns. Training and professional regulation vary by country, and the term does not necessarily mean the person is a medical doctor. Persistent or medically concerning hair-loss or scalp symptoms may require assessment by an appropriate healthcare professional.

U

UVA: Ultraviolet A radiation is a type of ultraviolet radiation that can contribute to premature skin aging and pigmentation. UVA can also pass through some types of glass, making broad-spectrum sun protection useful when appropriate.
UVB: Ultraviolet B radiation is a type of ultraviolet radiation that is a major cause of sunburn and contributes to skin-cancer risk. UVB intensity varies with factors such as time of day, season, location, and altitude.

V

Vitamin C (L-Ascorbic Acid): L-ascorbic acid is a form of vitamin C used in topical skincare. It is an antioxidant and is commonly included in products intended to improve the appearance of uneven tone and signs of photoaging. Vitamin C formulas can differ substantially in stability, concentration, and formulation. Explore our skincare guides.

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