Find Information About:

Drugs & Supplements

Get information and reviews on prescription drugs, over-the-counter medications, vitamins, and supplements. Search by name or medical condition.

Pill Identifier

Pill Identifier

Having trouble identifying your pills?

Enter the shape, color, or imprint of your prescription or OTC drug. Our pill identification tool will display pictures that you can compare to your pill.

Get Started

My Medicine

Save your medicine, check interactions, sign up for FDA alerts, create family profiles and more.

Get Started

WebMD Health Experts and Community

Talk to health experts and other people like you in WebMD's Communities. It's a safe forum where you can create or participate in support groups and discussions about health topics that interest you.

  • Second Opinion

    Second Opinion

    Read expert perspectives on popular health topics.

  • Community


    Connect with people like you, and get expert guidance on living a healthy life.

Got a health question? Get answers provided by leading organizations, doctors, and experts.

Get Answers

Sign up to receive WebMD's award-winning content delivered to your inbox.

Sign Up

Font Size

Hair Loss: Glossary


Biopsy: Piece of tissue cut out for microscopic examination

Bonding: A term used to describe the simple act of gluing a hairpiece onto the scalp.

Catagen: The intermittent stage between the growing (anagen) and resting (telogen) phases of the hair's growth cycle.

Chemotherapy: Chemical treatment, usually of cancers, using drugs that have high levels of toxicity, frequently causing temporary alopecia.

Club Hair: A hair that has stopped growing or is no longer in the anagen phase. It is anchored to the skin with its "club-like" root, but will eventually be pushed out and replaced by a growing hair.

Cobblestoning: "Plugs" that have not healed flush with the skin and therefore have left the scalp lumpy. "Plugs" seldom heal flush with the skin. Cobblestoning occurs in almost all "plug" procedures.

Cortex: The layer of the hair shaft that surrounds the medulla and is filled with keratin fibers. The main structural part of the hair fiber that accounts for most of its size and strength.

Crown: The highest part of the head.

Cuticle: The outer surface of hair, composed of overlapping scales made of colorless keratin protein. It gives hair luster and shine and also provides some of its strength.

Dermal Papilla: The dermal papilla is situated at the base of the hair follicle. The dermal papilla contains nerves and blood vessels, which supply glucose for energy and amino acids to make keratin. This structure is extremely important in the regulation of hair growth since it has receptors for both androgens and hair-promoting agents.

Dermis: One of the two layers of cells that form skin. Specifically, it is the innermost layer.

Diazoxide: A drug that dilates blood vessels by opening potassium channels and also promotes hair growth.

Dihydrotestosterone (DHT): Male hormone thought to be the main cause for the miniaturization of the hair follicle and for hair loss. DHT is formed when the male hormone testosterone interacts with the enzyme 5-alpha reductase.

Donor Site: Area where pieces of hair-bearing skin are taken from during a hair transplant.

Double Blind Study: A scientific study where neither the subjects nor the researchers know who specifically is receiving the drug of treatment under study.

1 | 2 | 3 | 4 | 5 | 6 | 7 | 8

Today on WebMD

hair in hairbrush
Ways to go about it naturally.
Young woman with thick curly hair
Causes and solutions.
man with thinning hair
How to keep the hair you have.
Closeup of Hairbrush with Hair Loss
Understand the basics.
Mens Hair Loss When To Start Treatment
A Dermatologist Talks About Hair Loss
Rogaine And Propecia For Hair Loss
Woman looking at thinning hair in hand mirror
Balding man in mirror
Close up of comb in woman's hair
Young woman with thick curly hair
hair problems