Glossary of Dermatology Terms

Have you recently received a diagnosis and are looking to better understand your skin condition? Or maybe you’re looking for more information online and are trying to wade through the medical jargon so that you can better advocate for your health? This glossary of terms frequently used in dermatology can help you to better understand your skin, hair, and nail health.

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Acral: involving the distal extremities of the body; examples include the fingers, ears, nose, toes, nipples, and penis.
Annular: ring-shaped.
Asymptomatic: a person showing no signs/symptoms of a condition that they have.
Biologic: a drug that is made from living organisms or parts of living organisms designed to target a specific part of the immune system that causes inflammation.
Biopsy: a medical procedure where they take a piece of tissue or a sample of cells from your body to be analyzed in a lab; most samples are taken using needles.
Bulla: raised lesion containing fluid; greater than 1 cm.
Burden of Disease: the physical, psychological, social, and economic impact of a disease on a person, family, institution, or society.
Carotenaemia: excessive beta-carotene circulating in the blood (beta carotene is derived from orange and yellow fruits and vegetables; our body turns beta carotene into vitamin A); causes yellow and orange skin colour and is prominent on soles and palms but does not affect the outer layer of the eye.
Clinician: a health care professional who works with patients/clients (e.g., doctors, nurses, physiotherapists, social workers, etc. who care for patients)
Comorbidity: When people have multiple illnesses/conditions at one time.
Cosmesis: preservation, restoration, or enhancement of physical beauty; surgical correction of a condition or the cosmetic improvements made after surgery.
Debridement: a procedure in which dead or infected skin is removed to promote wound healing.
Dermatomal: The area of skin supplied by a single spinal nerve (dermatome).
Dermatoses: Conditions affecting the skin, hair, or nails.
Diagnosis: the act of recognizing a disease or condition from its signs and symptoms. 
Ecchymosis: a discolouration of the skin usually caused by bleeding underneath the skin (sometimes caused by a bruise)
Efficacy: effectiveness; the ability to produce the desired effect
Erosion: loss of the outer layer of skin causing an open wound.
Erythema: increased blood supply causing redness; applicable to any skin condition that causes redness.
Erythroderma: redness affecting the whole body or almost the whole body.
Extensor: the side of a body part that extends a joint (e.g., back of the arms, front of the knees); it is on the opposite side of the limb or joint to flexor surfaces.
Fissure: painful crack in the skin; typically a straight line.
Flexor, flexural: the side of the body part that bends (or flexes) a joint; examples include armpits, backs of knees, groin, and elbow creases. It is on the opposite side of the extensor surfaces.
Follicular: lesions that appear in or around the roots (follicles) of hair.
Fomites: objects that are likely to carry infection, such as clothes, utensils, and furniture.
Generalised: widespread; covering many parts of the body.
Gyrate rash: a rash that appears as a pattern of wonky rings and wavy lines.
Herpetiform: small, raised bumps (papules) in a cluster that are solid.
Hyperpigmentation: darker skin than an individual’s normal skin colour; may be generalised or localized.
Hypopigmentation: paler than normal skin colour.
Incidence: the number of newly diagnosed cases of a disease. An incidence rate is the number of new cases of a disease divided by the number of people at risk for the disease.
Infarcts: interrupted blood supply causing blackness of dying tissue.
Inflammation: Puffy and/or red as a result of an immune response to a trigger (like an allergy) or a physical injury; it can also be purplish-grey. On lighter skin types, it appears red; on darker skin types, inflammation can appear a purplish-grey colour as well as red.
Jaundice: yellowing of the skin and the whites of the eye as a result of bile pigment buildup in the blood; often caused by liver disease or damage to the bile duct.
Lesion: any change in an area of the skin that looks different from the surrounding skin.
Leukoderma: whiteness of the skin; also referred to as achromia.
Lichenification: thickened or hard areas of skin due to frequent scratching or rubbing.
Linear lesion: a lesion in the shape of a straight/nearly straight line that often appears due to external reasons including scratching; also referred to as striate.
Localised: a condition which appears in [only] a specific area of the body.
Malodorous: having an unpleasant smell.
Macule: small patch of skin less than 1 cm that is not raised.
Morbidity: another word for illness.
Mortality: another word for death.
Nodule: raised lesion; greater than 1 cm.
Nummular lesion: circular (coin-shaped) lesions; also referred to as discoid.
Papule: a bump; less than or equal to 1 cm.
Patch: lesion greater than 1 cm that is not raised.
Perspiration: sweat
Petechiae: small (pinpoint-sized) red, purple, or brown spots caused by bleeding.
Photodistributive: a pattern of changes to the skin caused by excessive sun exposure (usually seen on areas that are often sun-exposed like forearms, cheeks, forehead, and nose).
Photosensitive: having an increased immune response to sunlight; usually causes itchiness, redness, and/or inflammation of the skin.
Plaque: raised lesion; greater than 1 cm.
Pressure areas: areas often prone to injury from pressure that are affected at rest:
  1. Tops of the ears; during sleep
  2. Buttocks; during sitting
  3. Heels; while lying down.
Prevalence: the total number of cases of a disease existing in a population. A prevalence rate is the total number of cases of a disease existing in a population divided by the total population number.
Pruritus: itchiness
Purpura: bleeding in the skin, such as a small red or purple spot (petechiae, less than 1 cm diameter) or discolouration of the skin (ecchymosis, more than 1 cm diameter), typically caused by bruising (ecchymoses); the skin does not turn white upon applying pressure to the area.
Purulent: containing or producing pus.
Pustule: raised bump containing pus; less than 1 cm.
Recurring: occurring again; returning after a period of time without symptoms.
Scaling: build-up of the outer layer of skin; followed by excessive shedding of the skin.
Seborrhoea: excessively oily skin caused by significantly more discharge of sebum, an oily substance that is released from sebaceous glands in the skin.
Seborrhoeic: relating to seborrhoea where there is significantly more discharge of sebum, a lubricating fatty matter; results in the appearance of oily skin and greasy scale formation.
Seborrhoeic keratosis: a non-cancerous warty growth.
Serum: dried pus, blood, or semen often mixed with dead skin cells.
Signs: objective, observable things that someone else can see which indicate a change in your health (e.g., a rash your doctor can see when you’re at your appointment).
Superficial: close to the surface; not very deep.
Symmetrical: similarities between the right and left side of the body.
Symptoms: a subjective experience or feeling that can only be identified by the person who has the condition (e.g., stomach cramps, headache, nausea, pain, etc).
Target lesion: a lesion made up of a series of rings around a central point, similar to an archery target (concentric circles); also referred to as iris lesion.
Telangiectasia: red or purple blood vessels that supply the skin.
Truncal: relating to or affecting the trunk/torso of a person; the area between the shoulders and the hips (not including the arms, legs, head, or neck).
Ulcer: a painful open wound. 
Ulceration: formation of an open sore or break on the skin or surface of an organ.
Unilateral: a rash only affecting one side of the body.
Vesicle: raised lesion containing fluid; less than or equal to 1 cm.
Violaceous: purple skin colouration.

Bolognia JL, Schaffer DJV, Cerroni L. Dermatology: 2-Volume Set. 4th ed. London, England: Elsevier Health Sciences; 2017.

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