Pronunciation: (hâr),[key] —n. 1. any of the numerous fine, usually cylindrical, keratinous filaments growing from the skin of humans and animals; a pilus.
2. an aggregate of such filaments, as that covering the human head or forming the coat of most mammals.
3. a similar fine, filamentous outgrowth from the body of insects, spiders, etc.
4. Bot.a filamentous outgrowth of the epidermis.
5. cloth made of hair from animals, as camel and alpaca.
6. a very small amount, degree, measure, magnitude, etc.; a fraction, as of time or space: He lost the race by a hair. 7. get in someone's hair,Slang.to annoy or bother someone: Their snobbishness gets in my hair. 8. hair of the dog,Informal.a drink of liquor, supposed to relieve a hangover: Even a hair of the dog didn't help his aching head.Also,hair of the dog that bit one. 9. let one's hair down,Informal. a. to relax; behave informally: He finally let his hair down and actually cracked a joke. b. to speak candidly or frankly; remove or reduce restraints: He let his hair down and told them about his anxieties. 10. make one's hair stand on end, to strike or fill with horror; terrify: The tales of the jungle made our hair stand on end. 11. split hairs, to make unnecessarily fine or petty distinctions: To argue about whether they arrived at two o'clock or at 2:01 is just splitting hairs. 12. tear one's hair, to manifest extreme anxiety, grief, or anger: He's tearing his hair over the way he was treated by them.Also,tear one's hair out. 13. to a hair, perfect to the smallest detail; exactly: The reproduction matched the original to a hair. 14. without turning a hair, without showing the least excitement or emotion. Also,not turn a hair.