Acacias meaning : A shrub or tree of the tribe Acacieae. 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. Gum arabic; gum acacia. Any of several related trees, such as the locust tree. A light to moderate greenish yellow with a hint of red. (history) A roll or bag, filled with dust, borne by Byzantine emperors, as a memento of mortality. It is represented on medals.