The generic name derives from ακακία (akakia), the name given by early Greek botanist-physician Pedanius Dioscorides (ca. 40-90) to the medicinal tree A. nilotica in his book Materia Medica.This name derives from the Greek word for its characteristic thorns, ακις (akis, thorn).The species name nilotica was given by Linnaeus from this tree's best-known range along the Nile river.
Acacias are also known as thorntrees, whistling thorns or wattles, including the yellow-fever acacia and umbrella acacias.
The genus Acacia previously contained roughly 1300 species, about 960 of them native to Australia, with the remainder spread around the tropical to warm-temperate regions of both hemispheres, including Europe, Africa, southern Asia, and the Americas. However, in 2005 the genus was divided into five separate genera. The name Acacia was retained for the majority of the Australian species and a few in tropical Asia, Madagascar and Pacific Islands. Most of the species outside Australia, and a small number of Australian species, were reclassified into Vachellia and Senegalia. The two final genera, Acaciella and Mariosousa, only contain about a dozen species from the Americas each.