a. Any of the cylindrical, keratinized, often pigmented filaments characteristically growing from the epidermis of a mammal.
b. A growth of such filaments, as that forming the coat of an animal or covering the scalp of a human.
2. A filamentous projection or bristle similar to a hair, such as a seta of an arthropod or an epidermal process of a plant.
3. Fabric made from the hair of certain animals: a coat of alpaca hair.
a. A minute distance or narrow margin: won by a hair.
b. A precise or exact degree: calibrated to a hair.
[Middle English her, from Old English hǣr.]
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2017 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
The American Heritage Dictionary Blog
Check out our blog, updated regularly, for new words and revised definitions, interesting images from the 5th edition, discussions of usage, and more.
American Heritage Dictionary Products
The American Heritage Dictionary, 5th Edition
The American Heritage Dictionary of Idioms
The American Heritage Roget's Thesaurus
Curious George's Dictionary
The American Heritage Children's Dictionary
The American Heritage Dictionary of Indo-European Roots
The American Heritage Student Grammar Dictionary
The American Heritage Desk Dictionary + Thesaurus
The American Heritage Science Dictionary
The American Heritage Dictionary of Business Terms
The American Heritage Student Dictionary
The American Heritage Essential Student Thesaurus