Definition of "acacia"

acacia¹

/əˈkeɪ.ʃə/

noun
countable and uncountable, plural acacias or acaciae
1. (countable) A shrub or tree of the tribe Acacieae.
  Quotations
  The latter species was collected only once in this survey on A. flavescens but is widespread on both tropical and temperate acacias in Australia.
  1997, Kenneth M. Old, Ian A. Hood, Zi Qing Yuan, Diseases of Tropical Acacias in Northern Queensland, K. M. Old, Su Lee See, J. K. Sharma (editors), Diseases of Tropical Acacias: Proceedings of an International Workshop held at Subanjeriji (South Sumatra) 28 April - 2 May 1996, page 1
2. (uncountable, pharmacy) The thickened or dried juice of several species in Acacieae, in particular Vachellia nilotica (syn. Acacia nilotica), the Egyptian acacia.
3. A false acacia; robinia tree, Robinia pseudoacacia.
4. (uncountable) Gum arabic; gum acacia.
5. (loosely) Any of several related trees, such as the locust tree.
6. A light to moderate greenish yellow with a hint of red.

acacia²

/əˈkeɪ.ʃə/

noun
plural acacias
1. (history, classical studies) A roll or bag, filled with dust, borne by Byzantine emperors, as a memento of mortality. It is represented on medals.