hair

Definitions

• (countable) A pigmented filament of keratin which grows from a follicle on the skin of humans and other mammals.
• (uncountable) The collection or mass of such growths growing from the skin of humans and animals, and forming a covering for a part of the head or for any part or the whole body.
• (zoology) A slender outgrowth from the chitinous cuticle of insects, spiders, crustaceans, and other invertebrates. Such hairs are totally unlike those of vertebrates in structure, composition, and mode of growth.
• (botany) A cellular outgrowth of the epidermis, consisting of one or of several cells, whether pointed, hooked, knobbed, or stellated.
• (countable) A locking spring or other safety device in the lock of a rifle, etc., capable of being released by a slight pressure on a hair-trigger.
• (obsolete) Haircloth; a hair shirt.
• (countable) Any very small distance, or degree; a hairbreadth.
• (slang) complexity; difficulty; quality of being hairy