Source : Webster's Revised Unabridged Dictionary (1913)

Acacia \A*ca"ci*a\, n. (Antiq.)
   A roll or bag, filled with dust, borne by Byzantine emperors,
   as a memento of mortality. It is represented on medals.

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}.

Source : WordNet®

acacia
     n : any of various spiny trees or shrubs of the genus Acacia