Like any other professional, the field of Aesthetics has its own terminology and verbage or language. I'll first define the words Aesthetics and Aesthetician because these two words will be frequently used throughout this site. They can also be spelled Esthetics and Esthetician. So Aesthetics is the branch of anatomical science that deals with the overall health and well-being of the skin.  From the Greek word aesthetikos, meaning “perceptible to the senses”. And Aesthetician is the Individual that practices in the field of aesthetics. 

Acid Mantel
Barrier on the surface of the skin formed by sebum and sweat.

Acne
A chronic inflammatory skin disorder of the sebaceous glands characterized by comedones and blemishes, also known as acne simplex or acne vulgaris.

Aesthetics

Branch of anatomical science that deals with the overall health and well-being of the skin.  From the Greek word aesthetikos, meaning “perceptible to the senses”.

Aesthetician
Individual that practices in the field of aesthetics.

Allantoin
Non-toxic element present in botanical extracts of the comfrey plant and uric acid from cows and most mammals, except humans and higher apes.  It is used in the manufacturing of cold cream, hand lotion, hair lotion, aftershave and other skin soothing cosmetics because of its ability to help heal wounds and skin ulcers.  Allantoin stimulates the growth of healthy tissue.

Aloe
The most  popular botanical used in cosmetic formulations; emollient and film-forming gum resin with hydrating, softening, healing, antimicrobial and anti-inflammatory properties.

Amino Acid
Building block of protein.

Anatomy

The study of the structure of the body that can be seen with the naked eye and what it is made of; the science of the structure of organisms or of their parts.

Antibacterial

Agent capable of killing bacteria outright.

Antioxidants

Substances that inhibit oxidation or reactions promoted by oxygen or peroxides.  Applied topically, antioxidants neutralize free radicals before they attach themselves to the cell membrane and destroy the cell.  To prevent oxidation, they are also added to cosmetic formulations.

Aromatherapy (essential) Oils
Highly concentrated plant oils that possess properties that have various effects on the skin, and the emotional and psychological systems; also called essential oils.

Bacteriostatic
Agent capable of inhibiting the growth or reproduction of bacteria.

Benzoyl Peroxide
A drying ingredient with antibacterial properties commonly used for blemishes and acne.  It can be a skin allergen and irritant.

Blood
Nutritive fluid circulating through the circulatory systems (heart, veins, arteries and capillaries) to supply oxygen and nutrients to cells and tissues, and to remove carbon dioxide and waste from them.

Cell
Basic unit of all living things; minute mass of protoplasm capable of performing all the fundamental functions of life.

Circulatory System
System that controls the steady circulation of the blood through the body by means of the heart and blood vessels.

Collagen
Protein fiber produced by fibroblasts which makes up 70 of the dermis.

Comedone
An open comedo or blackhead; a mass of hardened sebum and dead skin cells in a hair follicle.  When the follicle is filled with an excess oil, a blackhead forms.  It is dark because it is exposed to oxygen and oxidizes.  Closed comedones do not have a follicular opening and are called milia or whiteheads.

Comedogenicity
Tendency of any topical substance to cause or to worsen a buildup of dead cells in the follicle, leading to the development of a comedo (blackhead).

Cosmeceutical

A cosmetic product with pharmaceutical grade ingredients.   Besides the better quality and grade of ingredients, a Cosmeceutical product will have its ingredients fully disclosed, higher percentage of active agents and show results with its use.

Couperouse Skin
Redness, distended capillaries from weakening of the capillary walls.

Cyst
A close, abnormally developed sac containing fluid, infection, or other matter above or bellow the skin.

Delivery System

A means to deliver active ingredients to the skin.  In the cosmetic industry, delivery systems can come in the form of liposomes and polymers.  More recently, micro-encapsulation has been found to be a more suitable for of delivery system.

Dehydration
Lack of water.  Skin lines and roughness may be evident.

Dermis
Live layer of connective tissue below the epidermis.

Desquamation
Natural process in which skin cells are sloughed away and replaced.

Edema
Swelling caused by a response to injury or infection.

Erythema
Redness caused by inflammation, a red lesion is erythemic.

Excoriation
A skin sore or abrasion produced by scratching or scraping.

Exfoliant
Usually comes in the form of scrubs; water-based product containing a humectant mixed with some sort of abrasive agent such as almond meal or polyethylene granules.  More sophisticated and natural lines formulate their exfoliant with more natural materials such as bamboo beads.  Oftentimes these lines have both granules and enzymes for a better exfoliation.

Exfoliation
The peeling or sloughing of the outer layer of the skin.

Emollient
Emollients lie on the surface of the skin to prevent water loss and also fill in the lines of dry and dehydrated skin.  They soften and soothe the skin.

Emulsion
Mixture of two or more immiscible substances united with the aid of a binder or emulsifier.

Endocrine Glands
These are ductless glands (such as the thyroid, pituitary and suprarenal glands) that release hormonal secretions directly into the bloodstream.

Elastin
Protein fiber found in the dermis.

Epidermis
The outermost layer of skin; a thin, protective layer with many nerve endings.

Enzymes
Catalysts that break down complex molecules to utilize extracted energy.

Fats (lipids)
Macronutrient used to produce the materials in the sebaceous glands that lubricate the skin.

Fissure
A crack in the skin that penetrates the dermis.  Chapped lips or hands are fissures.

Fatty Acids
Lubricant ingredients derived from plant oil or animal fats.

Free Radical
Molecule which has lost one electron during some process.  This molecule becomes “defective” and cannot function properly.  It will go and “steal” the needed electron from another molecule.  If this behavior continues, soon a chain reaction will cause a significant number of “defective” molecules and this will cause damage to the body.

Glands
Specialized organs that remove certain constituents from the blood to convert them into new compounds.

Gommage
From the French, meaning “to erase”, gommage is a highly effective way of exfoliating the skin of the face and body.  It is applied to the skin of targeted area and let dry for about seven minutes.  It forms a hard crust and is then massaged off the skin leaving skin silky smooth.

Hormones
Secretion produced by one of the endocrine gland and carried by the bloodstream or body fluid to another part of the body or a body organ to stimulate functional activity or secretion.

Humectant
Ingredient that draws moisture to the skin and softens the surface, diminishing lines caused by dryness.  Glycerin is a humectant used in creams and lotions.

Hyaluronic Acid
A natural occurrence on the skin, hydrating fluids found between the fibers in the reticular layer.  Hydrophilic agent with excellent water-binding properties.

Hyperkeratosis
A thickening of the skin caused by a mass of keratinized cells (keratinocytes).

Hyperpigmentation
Overproduction of pigment.

Hypertrophy
An abnormal growth; many are benign or harmless.

Hypopigmentation
Lack of pigment.

Immiscible
Not capable of being mixed.

Integumentary System
The skin and its accessory organs, such as the oil and sweat glands, sensory receptors, hair and nails.

Jojoba Oil
Oil widely used in cosmetics, extracted from the beanlike seeds if the desert shrub.  Used as a lubricant and non-comedogenic emollient and moisturizer.

Keratin
Fiber protein that provides resiliency and protection to the skin.

Keratinocytes
Soft keratin which produce scale-like cells on the stratum corneum.

Keratosis
Abnormally thick build-up of cells.

Keratosis Pilaris
Redness and bumpiness in the cheeks or upper arms from blocked follicles.  Exfoliation can help unblock follicles and alleviate the rough feeling.

Langerhans Cells

Langerhans cells are found on the skin as well as other organs and is believed to be related to the immune system.  However, much controversy surrounds them as to their exact function.

Lanolin
Emollient with moisturizing properties and an emulsifier with high water absorption capabilities.

Lentigene

Also known as age spots, lentigenes are flat, brown, harmless spots. It usually appears on the back of the hands, on the neck and face as consequence of sun exposure.  Unless it changes in color, texture or size, there is no need for treatment, if not for aesthetics purpose.

Lesions
Structural changes in tissues caused by damage or injury.

Lipids
The lipids are a large and diverse group of naturally occurring organic compounds that are related by their solubility in non-polar organic solvents (e.g. ether, chloroform, acetone & benzene) and general insolubility in water.

Liposomes
Lipids used for micro-encapsulation delivery systems; hollow spheres made of lipids that are used to transport other agents, such as antioxidants, into the skin.

Lymph
Clear yellowish fluid that circulates in the lymph spaces (lymphatic) of the body; carries wast and impurities away from the cells.

Lymph nodes
Gland-like bodies in the lymphatic vessels that filter lymph.

Macule
A flat spot or discoloration on the skin, such as a freckle.  Macules are neither raised nor sunken.

Medical Aesthetics
Integration of surgical procedures and aesthetics treatments.

Melanin
Pigment that gives the skin its color.  It is part of the defense mechanisms of the skin to protect it from the sun.

Melanocytes
Cells that produce pigment granules in the basal layer.

Melanoma

The most serious kind of skin cancer, it develops in the cells that produce melanin.  Melanomas can also be formed in the eyes and, rarely, in internal organs such as the intestines.

Melasma
Term for hyperpigmentation; pregnancy mask is often called melasma.  This is triggered by hormonal changes and can fade with time.

Milia
Also called whiteheads, milia are whitish, pearly-like masses of sebum and dead cells under the skin.  Milia are more common in dry skin types and may form after skin trauma, such as a laser resurfacing.

Miscible
Capable of being mixed with another liquid in any proportion without separating.

Mitosis
Process by which cells divide into two new cells (daughter cells); the usual process of cell reproduction of human cells.

Nodule
Also referred to as tumor, a nodule is smaller bumps caused by conditions such as scar tissue, fatty deposits or infections.

Nonpathogenic
Not harmful to one’s health; not disease-producing.

Oxidation
Chemical reaction that combines an element or compound with oxygen to produce an oxide.

Organ
Structure composed of specialized tissues and performing specific functions.

Pappilary Layer
Layer that connects the dermis to the epidermis.

Papule
A pimple; small elevation on the skin that contains no fluid, but may contain pus.

Parabens
One of the most commonly used groups of preservatives in the cosmetic, pharmaceutical and food industries provide bacteriostatic and fungistatic activity against a diverse number of organisms and are considered safe for use in cosmetics.

Pathogenic
Causing disease; harmful to one’s health.

Performance or Active Ingredients
Ingredients in cosmetic products that cause the actual changes in the appearance of the skin.

pH
Relative degree of acidity and alkalinity of a substance.  The pH of the acid mantle is between 4.5 and 6.2, the ideal being 5.5.

Physiology
Study of the functions or activities performed by the body’s structures.

Proteins
Chains of amino acid molecules used in body growth.

Protoplasm
Colorless jelly-like substance in cells in which food elements such as protein, fats, carbohydrates, mineral salts and water are present.

Psoriasis
A skin disease characterized by red patches covered with white-silver scales.  It is caused by an over-proliferation of skin cells that replicate too fast.  Immune dysfunction could be the cause.  Psoriasis is usually found in patches on the scalp, elbows, knees, chest and lower back.

Pustule
An inflamed papule with a white or yellow center containing pus, a fluid consisting of white blood cells, bacteria and other debris produced from an infection.

Retinoic Acid (Retin A)
A vitamin A derivative.  It has demonstrated an ability to alter collagen synthesis and is used to treat acne and visible signs of aging.  Side effects are irritation, photosensitivity, skin dryness, redness and peeling.

Reticular layer
The deeper layer of the dermis, containing proteins that give the skin its strength and elasticity.

Rosacea
A chronic congestion primarily on the cheeks and nose and is characterized by redness, dilation of blood vessels.   In severe cases, the formation of papules and pustules will occur in the last stages of the condition and will be called acne rosacea.  Although the cause is still not fully known, ethnicity is one of the factors.  It is also know that the condition will manifest more frequently in women, but men will also be afflicted and in a more severe degree.

Salicylic Acid
A betahydroxy acid (BHA) with exfoliating and antiseptic properties, natural sources include sweet birch, willow bark and wintergreen.

Sebaceous Glands
Glands that secrete oil to keep the skin soft and protected.

Sebum
Oil secreted by the sebaceous gland.  It provides protection from external factors for the epidermis and lubricates both the skin and hair.

Secretion
A product manufactured by a gland for a special purpose,  Secretions are produced between skin cells and from the sebaceous glands in hair follicles.

Serum
User-friendly versions of ampoules, intended for a specific corrective treatment used day and night for 30 to 60 days or more.  Concentrated liquid ingredients for the skin designed to penetrate and treat various skin conditions.

Skin Tag
Small outgrowths pr extensions of the skin that look like flaps.  They are benign and are common under the arms or on the neck.

Sorbitol
Humectant that absorbs moisture from the air to prevent skin dryness.

Squalane
Derived from olives, it desensitizes and nourishes; an emollient.

Stratum Corneum
Outermost layer of the epidermis.

Statum Germinativum
First layer of the epidermis above the pappilary layer of the dermis, also known as basal layer.

Stratum Granulosum
Layer composed of cells resembling granules, which replace cells shed from the stratum corneum.

Stratum Lucidum
Clear layer under the stratum corneum, only found on the palms of the hands and soles of feet.

Stratum Spinosum
Spiny layer above the basal layer; not always listed as a separate layer.

Sudoriferous (sweat) Glands
Gland responsible for the excretion of perspiration and detoxification of the body.  It does so by excreting excess salt and unwanted chemicals.

Titanium Dioxide
Non-chemical ingredient that blocks UV rays.

T-Zone
The center area of the face corresponding to the forehead, nose and chin.

UVA Rays
Also called “aging rays”, these contribute 90 to 95 percent of the sun’s UV rays that reach the earth’s surface.

UVB Rays
Also called “burning rays”, these cause tanning of the skin by affecting by affecting melanocytes.

Vellus Hair

Short, fine, light-colored, barely noticeable hair that develops on most of a person's body from his/her childhood.

Virus
Submicroscopic structure capable of infesting almost all plants and animals, including bacteria; infectious agent that lives only by penetrating cells and becoming part of them.

Zinc Oxide
Used to protect, soothe and heal the skin.  Provides an excellent barrier to the sun and other irritants.  It is somewhat astringent, antiseptic and antibacterial.