1540s, type of shrub or tree fund in warm climates of Africa and Australia, from Latin acacia, from Greek akakia "thorny Egyptian tree," a word of uncertain origin. Perhaps it is related to Greek akē "point, thorn" (from PIE root *ak- "be sharp, rise (out) to a point, pierce"), or perhaps it is a Hellenization of some Egyptian word. Beekes suggests it is probably a word from a pre-Greek Mediterranean language and finds "no reason for an Oriental origin." Greek kaktos also has been compared. From late 14c. in English as the name of a type of gum used as an astringent, etc. Extended 17c. to North American trees.