noun

• (countable) A shrub or tree of the tribe Acacieae.
• (uncountable, pharmacy) The thickened or dried juice of several species in Acacieae, in particular Vachellia nilotica (syn. Acacia nilotica), the Egyptian acacia.
• A false acacia; robinia tree, Robinia pseudoacacia.
• (uncountable) Gum arabic; gum acacia.
• (loosely) Any of several related trees, such as the locust tree.
• A light to moderate greenish yellow with a hint of red.
• (history, classical studies) A roll or bag, filled with dust, borne by Byzantine emperors, as a memento of mortality. It is represented on medals.