1. (printing) the narrowest of the spaces used to separate words or letters
The Collaborative International Dictionary of English v.0.48:
Hair \Hair\ (h[^a]r), n. [OE. her, heer, h[ae]r, AS. h[=ae]r;
akin to OFries. h[=e]r, D. & G. haar, OHG. & Icel. h[=a]r,
Dan. haar, Sw. h[*a]r; cf. Lith. kasa.]
1. The collection or mass of filaments growing from the skin
of an animal, and forming a covering for a part of the
head or for any part or the whole of the body.
2. One the above-mentioned filaments, consisting, in
vertebrate animals, of a long, tubular part which is free
and flexible, and a bulbous root imbedded in the skin.
Then read he me how Sampson lost his hairs.
And draweth new delights with hoary hairs.
3. Hair (human or animal) used for various purposes; as, hair
for stuffing cushions.
4. (Zool.) 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.
5. (Bot.) An outgrowth of the epidermis, consisting of one or
of several cells, whether pointed, hooked, knobbed, or
stellated. Internal hairs occur in the flower stalk of the
yellow frog lily (Nuphar).
6. A spring device used in a hair-trigger firearm.
7. A haircloth. [Obs.] --Chaucer.
8. Any very small distance, or degree; a hairbreadth.
Note: Hairs is often used adjectively or in combination; as,
hairbrush or hair brush, hair dye, hair oil, hairpin,
hair powder, a brush, a dye, etc., for the hair.
Against the hair, in a rough and disagreeable manner;
against the grain. [Obs.] "You go against the hair of your
Hair bracket (Ship Carp.), a molding which comes in at the
back of, or runs aft from, the figurehead.
Hair cells (Anat.), cells with hairlike processes in the
sensory epithelium of certain parts of the internal ear.
Hair compass, Hair divider, a compass or divider capable
of delicate adjustment by means of a screw.
Hair glove, a glove of horsehair for rubbing the skin.
Hair lace, a netted fillet for tying up the hair of the
Hair line, a line made of hair; a very slender line.
Hair moth (Zool.), any moth which destroys goods made of
hair, esp. Tinea biselliella.
Hair pencil, a brush or pencil made of fine hair, for
painting; -- generally called by the name of the hair
used; as, a camel's hair pencil, a sable's hair pencil,
Hair plate, an iron plate forming the back of the hearth of
a bloomery fire.
Hair powder, a white perfumed powder, as of flour or
starch, formerly much used for sprinkling on the hair of
the head, or on wigs.
Hair seal (Zool.), any one of several species of eared
seals which do not produce fur; a sea lion.
Hair seating, haircloth for seats of chairs, etc.
Hair shirt, a shirt, or a band for the loins, made of
horsehair, and worn as a penance.
Hair sieve, a strainer with a haircloth bottom.
Hair snake. See Gordius.
Hair space (Printing), the thinnest metal space used in
lines of type.
Hair stroke, a delicate stroke in writing.
Hair trigger, a trigger so constructed as to discharge a
firearm by a very slight pressure, as by the touch of a
Not worth a hair, of no value.
To a hair, with the nicest distinction.
To split hairs, to make distinctions of useless nicety.
[1913 Webster] hairball
WordNet (r) 3.0 (2006):
n 1: (printing) the narrowest of the spaces used to separate
words or letters