Beauty & Skincare Glossary

The ultimate A-Z Beauty Glossary to Make You An Expert. This is our insider beauty dictionary, an ABC of products, ingredients and terminologies that will make you the go-to for beauty and skincare knowledge. 

Beauty & Skincare Glossary - SKIIN COMPANY


Having a pH (“potential hydrogen”) less than 7. The skin’s barrier, or acid mantle, is naturally slightly acidic, with a pH hovering around 4.5 to 5.5. When it drops out of range, skin becomes prone to breakouts and irritation.


Alanine is an α-amino acid that is used in the biosynthesis of proteins. It contains an amine group and a carboxylic acid group, both attached to the central carbon atom which also carries a methyl group side chain. 


Undrinkable ethyl alcohol has many uses in skin care. It delivers other ingredients into the skin and drives them deeper down. In toners and acne products, it can help dissolve oil and temporarily tighten pores. When added to certain moisturizers, like gel-based lotions, it makes them less tacky and helps them dry down faster on the face.


Having a pH (“potential hydrogen”) greater than 7. Alkaline substances are also known as “basic” — the opposite of acidic. When skin is too alkaline — as a result of eating the wrong foods or using the wrong products — it gets dry, irritated, inflamed, and more prone to wrinkling.


This fatty acid found in all cells in the body contributes to skin’s smoothness. It dissolves in both fat and water, enabling it to penetrate well into all parts of skin cells.


The building blocks of the proteins that make up collagen and elastin — substances that give the skin its structural support. Aging and a combination of external factors (including UV light and environmental toxins) reduce the level of amino acids in the body; creams containing amino acids may help restore them.


Any ingredient that reduces free-radical damage to the skin.


A critical building block of proteins, skin collagen and hair keratin. It helps blood vessels relax, so more oxygen-rich blood can circulate through your arteries.


This peptide is marketed as “Botox in a cream” because of its apparent ability to temporarily prevent tensing of facial muscles.


Also known as l-ascorbic acid, this topical form of antioxidant vitamin C, brightens the skin, increases collagen production, and stems free-radical damage, making it a popular ingredient.


Aspartic acid is an α-amino acid that is used in the biosynthesis of proteins. Aspartic acid is commonly used to reduce feelings of tiredness, improve athletic performance, and increase the size and strength of muscles.


A red-orange pigment found in certain fruits and vegetables, it’s a precursor to vitamin A (retinol); upon ingestion, the body converts beta carotene into antioxidant vitamin A, which helps maintain skin and eye health. It’s essential for normal cell growth and turnover, and may help improve the skin’s tone and texture.


These chemical exfoliants can smooth fine lines, even pigmentation, and penetrate deeply into pores, dissolving sticky plugs of sebum and dead skin. One of the most common BHAs, salicylic acid, is found in many acne washes, creams, and peels.


Small amounts of this B vitamin are found in carrots, almonds, milk, and other foods. Aside from helping the body process fats and sugars, oral biotin is important for regulating hair and nail growth. Shampoos and conditioners containing it claim the ingredient reduces hair breakage and increases elasticity.


A label applied to sunscreens that offer protection against both UVA and UVB rays, both of which contribute to your risk for skin cancer.


An anti-inflammatory enzyme culled from the stem or fruit of the pineapple plant. Some aesthetic doctors recommend eating fresh pineapple or taking homeopathic bromelain supplements in the days before and after cosmetic injections to minimize bruising and swelling.


Affecting up to 90 percent of women (due to estrogen and genetics), cellulite occurs when fat cells swell and push through the tight, fibrous tissue bands (or septa) walling them in, creating a dimpled or lumpy appearance. Only about 10 percent of men suffer cellulite, as their septa is constructed differently, and better able to contain fat cells to prevent bulging.


Found in many fruits, the antioxidant alpha hydroxy acid acts as a natural preservative. When used in peels, masks, and washes, it brightens and exfoliates the upper layers of the skin, encouraging new collagen formation.


Levels of this antioxidant in the skin decline with age and UV exposure. CoQ10 is added to fine line-fighting products to preserve skin-cell function and improve skin texture.


This protein makes up 80 percent of the skin, and its fibers give skin its firmness and strength. Collagen naturally breaks down over time, but certain ingredients, such as retinol and peptides (including Matrixyl), can stimulate new collagen production. The most abundant protein in the human body, it makes skin thick, strong, and smooth. Laser treatments and retinoids build it up; UV rays and free radicals tear it down.


A natural carbohydrate, DHA is the active ingredient in most sunless tanners.


Highly unstable molecules created in the body by sunlight, cigarette smoke, and pollution that latch onto and damage cells in ways that can lead to roughness, sagging, and wrinkling.


Found throughout the human body, the antioxidant, anti-inflammatory ingredient has long been used as an oral supplement to relieve arthritis. Research shows that topical application may reduce hyperpigmentation and boost hyaluronic acid production, smoothing fine lines and wrinkles.


In addition to protein synthesis, glutamic acid has several key functions within the body. It acts as an important neurotransmitter and the body uses it to create other neurotransmitters, such as GABA. Thus, this amino acid is critical for healthy brain development and function.


Glycine is an amino acid that functions as a building block for certain proteins, most especially the collagen found in skin, ligaments, muscles, bones, and cartilage. It significantly improves skin elasticity in women, improves skin hydration and prevents water loss. In addition, Glycine stimulates the production of the serotonin, the “feel good” hormone that helps elevate mood, improve sleep quality, and enhance cognition and memory.


This age-accelerating process occurs when sugar molecules in the bloodstream bind to protein tissue throughout the body, creating advanced glycation end products (AGEs), free-radical damage, and inflammation. Among the tissues affected are the collagen and elastin fibers responsible for keeping skin smooth, plump, and flexible, which is why scientists now link a chronically high-glycemic diet to premature wrinkling and sagging.


A hydrating ingredient used commonly in moisturising products. It’s a humectant, meaning it pulls moisture from the atmosphere to hydrate skin. Commonly used in moisturizers and hydrating cleansers, this is an inexpensive ingredient.


Boasting antioxidant levels that are far more powerful than vitamins E and C, topical and oral formulations of the ingredient are used to protect the skin against UV damage and other environmental assaults.


Extracted directly from green-tea leaves, this potent antioxidant fights free radicals and quells inflammation. It’s typically used in face creams and lotions.


Histidine is an amino acid needed in humans for growth and tissue repair, Histidine is important for protecting nerve cells and is required for blood cell manufacture and protects tissues against damage caused by radiation and heavy metals.


Hyaluronic acid is found naturally in the skin. It has the properties of combining collagen fibers and binding molecules of water, provides us with firm, moisturized and nourished skin. Interestingly, only one gram of hyaluronic acid can bind about six liters of water. An additional advantage of HA is that it can also alleviate inflammation. With age, however, its amount in the skin decreases, which leads to the formation of wrinkles. 


Found in beauty supplements and drinks aiming to plump and hydrate the skin, these collagen proteins have been broken down into smaller peptides to make for easier absorption into the bloodstream.


Hydroxyproline is a major component of the protein collagen. Hydroxyproline is produced by hydroxylation of the amino acid proline. Hydroxyproline and proline play key roles in collagen stability.


Hydroxylysine, glycogenic amino acid uniquely found in collagen, the chief structural protein of mammalian skin and connective tissue.


A wrinkle-fighting form of vitamin A shown to be less irritating and more stable than traditional retinol.


is considered to be glucogenic amino acids, meaning those that the body can easily and quickly transform into the energy necessary for its functioning. This means that we will be able to not only train longer and more intensively, but also to regenerate faster. 


A category of skin-care products (essences, sheet masks, cushion compacts), rituals (à la double-cleansing and multi-step routines), and trends (hi, glass skin) hailing from South Korea that emphasizes healthy, hydrated, glowy, no-makeup skin.


Derived from fermented milk, this alpha hydroxy acid exfoliates dead skin cells and is gentle enough for people with sensitive skin or rosacea. Since it’s part of our natural moisturizing factor, it’s especially compatible with human skin.




Participates in the production of proteins that build muscles and bones mainly. It helps to keep youth and beautiful figure. Because our body cannot produce it itself, it must be provided in the form of supplements. 


The pigment that gives hair, skin, and eyes their color; patches of excess melanin can cause dark spots.


has diverse physiological functions, such as assisting wound healing, detoxification of nitrogenous wastes, stimulating immune function, and promoting secretion of several hormones.


A mix of purified water, hydrators (like glycerin), and low doses of mild surfactants, these no-rinse liquid cleansers attract makeup, oil, and dirt when swiped over skin with a cotton pad. They’re mild enough for sensitive and acne-prone complexions.


A form of Vitamin B3, Niacinamide helps to strengthen skin and improve elasticity whilst reducing redness.


L-norvaline is a compound that can boost your body’s performance and aid recovery.


An active ingredient in sunscreens, this clear, colorless chemical offers only limited protection against UVA and UVB rays on its own, but can stabilize and strengthen the sun-protective powers of any UV filters it’s combined with.


A class of preservatives used to protect cosmetics against the growth of bacteria and fungi. These controversial ingredients — including methylparaben, propylparaben, and butylparaben — have been shown to possess weak estrogen-like properties, but the FDA deems them safe when used at very low levels (.01 to .3 percent) in cosmetics.


A trademarked class of sunscreen ingredients that absorb specific wavelengths of UVB and UVA light, minimizing photo damage to the skin. The most widely used, Parsol 1789 (known generically as avobenzone), absorbs UVA rays. Many broad-spectrum sunscreens pair the ingredient with others that filter out UVB light.


These are chains of amino acids, which are the building blocks of protein. Your skin is made up of proteins, like collagen, and peptides stimulate this collagen production. For that reason, peptides are prominent in anti-aging products that promote collagen growth and help repair skin.


A measure of the acidity or alkalinity of a substance. Water has a neutral pH of 7. A healthy skin barrier has an acidic pH of 4.5 to 5.5. And pH-balanced skin-care products generally fall on the slightly acidic side of neutral.


Phenylalanine is an essential α-amino acid. Too little phenylalanine curbs physical and intellectual growth. 


Proline is a basic amino acid involved in the synthesis of collagen. L-proline allows to maintain healthy joints, stimulates the regeneration processes of joint cartilage and muscles, and supports the maintenance of good condition of the skin, hair and nails.


Beneficial strains of live bacteria that can be ingested through fermented foods and supplements, or applied topically (via certain mists, creams, and serums) to improve gut and skin health.


The brand name for the prescription vitamin A derivative tretinoin. First approved by the FDA for the treatment of acne, Retin-A was eventually found to fight signs of aging by speeding up exfoliation, repairing skin on a molecular level, and boosting new collagen production.


This is the catchall phrase used to describe all vitamin A derivatives used in skin care.


A derivative of vitamin A used in fine line-fighting products to stimulate the turnover of skin cells and increase collagen production. The maximum amount allowed in over-the-counter products is 1 percent. Retinyl palmitate and retinaldehyde are weaker, less-irritating forms of retinol.


A chronic skin disease marked by persistent redness, easy flushing, broken blood vessels, and pimples on the nose and cheeks primarily. Rosacea tends to run in families, especially those of Northern or Eastern European descent. The cause is unknown; there is no cure; and controlling triggers (heat, UV, spicy foods, alcohol) is crucial to treatment.


A beta hydroxy acid that removes excess oil and dead cells from the skin’s surface. It’s used in nonprescription cleansers, moisturizers, and treatments for acne-prone skin in concentrations of 0.5 to 2 percent.


A skin-care product that contains high concentrations of active ingredients and claims superior penetration of the skin’s surface when applied.


L-serine is an amino acid essential for the synthesis of phosphatidylserine, which is a component of the membrane of brain cells (i.e., neurons). It can be produced in the body, including the brain, but an external supply from the diet is essential in maintaining necessary levels.


L-tryptophan is an essential amino acid that helps the body make proteins and certain brain-signaling chemicals. Your body changes L-tryptophan into a brain chemical called serotonin. Serotonin helps control your mood and sleep.








Vitamin A is a key vitamin when it comes to the health of our skin, hair and nails. That is why it is often an invaluable component of skin and hair supplements. The use of vitamin is particularly important for dry and acne-prone skin. It helps the skin to maintain an adequate level of hydration, thanks to which the skin is more elastic and softer. It also helps in the fight against signs of aging such as wrinkles. It proves helpful in reducing stretch marks or symptoms of flaky skin.




Vitamin B3, or niacinamide, as it is also called, is known in skin care as a soothing moisturizer. The vitamin increases ceramide production in the skin and strengthens the skin’s barrier function, which is the key to locking in moisture and keeping irritants and pollutants away. Vitamin B3 has also historically been popular in the fight against acne. It has also long been used for hyperpigmentation in the skin (hyperpigmentation is darkened areas of the skin due to sun damage or inflammation.


An antioxidant that boosts collagen production and inhibits pigment formation. Like many antioxidants, it’s an unstable molecule that can break down quickly when exposed to light and air. Common derivatives, like ascorbyl palmitate and tetrahexyldecyl ascorbate, tend to be more stable than pure ascorbic acid but slower acting.


This moisturizing antioxidant protects against free-radical damage.


Biotin is a vitamin that’s a part of the vitamin B family, it’s also known as vitamin H. The word “biotin” comes from the ancient Greek word “biotos,” which means “life” or “sustenance.” B vitamins, and specifically biotin, help keep your skin, hair, eyes, liver, and nervous system healthy. Biotin is also a crucial nutrient Trusted Source during pregnancy, as it’s important for embryonic growth.


Tau protein promotes assembly and stabilizes microtubules, which contributes to the proper function of neuron.



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