Gum \Gum\, n. [OE. gomme, gumme, F. gomme, L. gummi and commis,
fr. Gr. ?, prob. from an Egyptian form kam?; cf. It.
gomma.]
1. A vegetable secretion of many trees or plants that hardens
when it exudes, but is soluble in water; as, gum arabic;
gum tragacanth; the gum of the cherry tree. Also, with
less propriety, exudations that are not soluble in water;
as, gum copal and gum sandarac, which are really resins.
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2. (Bot.) See Gum tree, below.
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3. A hive made of a section of a hollow gum tree; hence, any
roughly made hive; also, a vessel or bin made of a hollow
log. [Southern U. S.]
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4. A rubber overshoe. [Local, U. S.]
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Black gum, Blue gum, British gum, etc. See under
Black, Blue, etc.
Gum Acaroidea, the resinous gum of the Australian grass
tree (Xanlhorrh[oe]a).
Gum animal (Zool.), the galago of West Africa; -- so called
because it feeds on gums. See Galago.
Gum animi or anim['e]. See Anim['e].
Gum arabic, a gum yielded mostly by several species of
Acacia (chiefly A. vera and A. Arabica) growing in
Africa and Southern Asia; -- called also gum acacia.
East Indian gum arabic comes from a tree of the Orange
family which bears the elephant apple.
Gum butea, a gum yielded by the Indian plants Butea
frondosa and B. superba, and used locally in tanning
and in precipitating indigo.
Gum cistus, a plant of the genus Cistus (Cistus
ladaniferus), a species of rock rose.
Gum dragon. See Tragacanth.
Gum elastic, Elastic gum. See Caoutchouc.
Gum elemi. See Elemi.
Gum juniper. See Sandarac.
Gum kino. See under Kino.
Gum lac. See Lac.
Gum Ladanum, a fragrant gum yielded by several Oriental
species of Cistus or rock rose.
Gum passages, sap receptacles extending through the
parenchyma of certain plants (Amygdalace[ae],
Cactace[ae], etc.), and affording passage for gum.
Gum pot, a varnish maker's utensil for melting gum and
mixing other ingredients.
Gum resin, the milky juice of a plant solidified by
exposure to air; one of certain inspissated saps, mixtures
of, or having properties of, gum and resin; a resin
containing more or less mucilaginous and gummy matter.
Gum sandarac. See Sandarac.
Gum Senegal, a gum similar to gum arabic, yielded by trees
(Acacia Verek and A. Adansoni[aum]) growing in the
Senegal country, West Africa.
Gum tragacanth. See Tragacanth.
Gum water, a solution of gum, esp. of gum arabic, in water.
Gum wood, the wood of any gum tree, esp. the wood of the
Eucalyptus piperita, of New South Wales.
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Elastic \E*las"tic\ ([-e]*l[a^]s"t[i^]k), a. [Formed fr. Gr.
'elay`nein to drive; prob. akin to L. alacer lively, brisk,
and E. alacrity: cf. F. ['e]lastique.]
1. Springing back; having a power or inherent property of
returning to the form from which a substance is bent,
drawn, pressed, or twisted; springy; having the power of
rebounding; as, a bow is elastic; the air is elastic;
India rubber is elastic.
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Capable of being drawn out by force like a piece of
elastic gum, and by its own elasticity returning,
when the force is removed, to its former position.
--Paley.
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2. Able to return quickly to a former state or condition,
after being depressed or overtaxed; having power to
recover easily from shocks and trials; as, elastic
spirits; an elastic constitution.
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Elastic bitumen. (Min.) See Elaterite.
Elastic curve.
(a) (Geom.) The curve made by a thin elastic rod fixed
horizontally at one end and loaded at the other.
(b) (Mech.) The figure assumed by the longitudinal axis of
an originally straight bar under any system of bending
forces. --Rankine.
Elastic fluids, those which have the property of expanding
in all directions on the removal of external pressure, as
the air, steam, and other gases and vapors.
Elastic limit (Mech.), the limit of distortion, by bending,
stretching, etc., that a body can undergo and yet return
to its original form when relieved from stress; also, the
unit force or stress required to produce this distortion.
Within the elastic limit the distortion is directly
proportional to the stress producing it.
Elastic tissue (Anat.), a variety of connective tissue
consisting of a network of slender and very elastic fibers
which are but slightly affected by acids or alkalies.
Gum elastic, caoutchouc.
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Caoutchouc \Caout"chouc\, n. [F. caoutchouc, from the South
American name.]
A tenacious, elastic, gummy substance obtained from the milky
sap of several plants of tropical South America (esp. the
euphorbiaceous tree Siphonia elastica or Hevea
caoutchouc), Asia, and Africa. Being impermeable to liquids
and gases, and not readly affected by exposure to air, acids,
and alkalies, it is used, especially when vulcanized, for
many purposes in the arts and in manufactures. Also called
India rubber (because it was first brought from India, and
was formerly used chiefly for erasing pencil marks) and gum
elastic. See Vulcanization.
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Mineral caoutchouc. See under Mineral.
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