The Collaborative International Dictionary of English v.0.48:
acacia \a*ca"cia\ ([.a]*k[=a]"sh[.a] or [.a]*k[=a]"sh[i^]*[.a]),
n.; pl. E. acacias ([.a]*k[=a]"sh[.a]z), L. acaciae
([.a]*k[=a]"sh[i^]*[=e]). [L. from Gr. 'akaki`a; orig. the
name of a thorny tree found in Egypt; prob. fr. the root ak
to be sharp. See Acute.]
1. [capitalized] 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. AS
[1913 Webster] Acacin