Source : Webster's Revised Unabridged Dictionary (1913)

Acacia \A*ca"cia\, n.; pl. E. {Acacias}, L. {Acaci[ae]}. [L.
   from Gr. ?; orig. the name of a thorny tree found in Egypt;
   prob. fr. the root ak to be sharp. See {Acute}.]
   1. A genus of leguminous trees and shrubs. Nearly 300 species
      are Australian or Polynesian, and have terete or
      vertically compressed leaf stalks, instead of the
      bipinnate leaves of the much fewer species of America,
      Africa, etc. Very few are found in temperate climates.

   2. (Med.) The inspissated juice of several species of acacia;
      -- called also {gum acacia}, and {gum arabic}.

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.

   2. (Bot.) See {Gum tree}, {below}.

   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.]

   4. A rubber overshoe. [Local, U. S.]

   {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} (Zo["o]l.), 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["a]}) growing in the
      Senegal country, West Africa.

   {Gum tragacanth}. See {Tragacanth}.

   {Gum tree}, the name given to several trees in America and
      Australia:
      (a) The black gum ({Nyssa multiflora}), one of the largest
          trees of the Southern States, bearing a small blue
          fruit, the favorite food of the opossum. Most of the
          large trees become hollow.
      (b) A tree of the genus {Eucalyptus.} See {Eucalpytus.}
      (c) The sweet gum tree of the United States ({Liquidambar
          styraciflua}), a large and beautiful tree with
          pointedly lobed leaves and woody burlike fruit. It
          exudes an aromatic terebinthine juice.

   {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.

Source : WordNet®

gum acacia
     n : gum from an acacia tree; used as a thickener (especially in
         candies and pharmaceuticals) [syn: {gum arabic}]