2. Especially, in humans and other mammals, one of the filamentous appendages consisting of keratin and growing out of the skin, or of the scalp.
Each hair consists of a cylindrical shaft and a root, which is contained in a flasklike depression (hair follicle) in the corium and subcutaneous tissue. The base of the root is expanded into the hair bulb, which rests upon and encloses the hair papilla.
The three phases from production of a hair to its final shedding are called the hair cycle.
2. Any of the numerous fine, usually cylindrical, keratinous filaments growing from the skin of humans and animals; a pilus.
3. An aggregate of such filaments, as that covering the human head or forming the coat of most mammals.
4. A similar fine, filamentous outgrowth from the body of insects, spiders, etc.
5. Plants: a filamentous outgrowth of the epidermis.
6. Cloth made of hair from animals; such as, camel and alpaca.
7. A very small amount, degree, measure, magnitude, etc.; a fraction, as of time or space: "He lost the race by a hair."
8. To get into someone's hair; slang, to annoy or bother someone.
9. To let one's hair down:
To relax; behave informally: "She finally let her hair down and actually started to talk to us."
To speak candidly or frankly; to remove or to reduce restraints: "He let his hair down and told them about his marital problems."
11. To split hairs, to make unnecessarily fine or petty distinctions: "To argue about whether they arrived at two o'clock or at one minute after two is just splitting hairs."
12. To tear out one's hair is to manifest extreme anxiety, grief, or anger.
13. To a hair, perfect to the smallest detail; exactly: "The copy matched the original production to a hair."
14. Without turning a hair, without showing the least excitement or emotion.
15. A ball of hair: an accumulation of hair in the stomach or intestines of a cat or other animal as a result of the animal's licking its coat.
Some people say that rabbit fur is really simply hare hair.
Generally, the rate of hair growth increases and the thickness of the hairs increases in direct proportion to the androgen levels; however, different areas respond with different sensitivities.
As puberty progresses, the sequence of appearance of sexual (androgenic) hair reflects the gradations of androgen sensitivity. The pubic area is most sensitive, and heavier hair usually grows there first in response to androgens.
The follicle is lined by cells derived from the epidermal (outside) layer of the skin.
Each follicle normally goes through a five-year cycle of growth and rest, with about 90% of the follicles growing hair at any one time, averaging about six inches (15 cm) of growth per year.
Derived from the Latin word follis, "bag".
Excerpts of information about hair from several sources
2. A description of a plant or plant part covered with long stiff hairs; "It was an abnormally hirsute leaf."
3. Bearing coarse, rough, longish hairs.