Today it means: An edible substance taken from one of two species of sub-Saharan acacia trees, Senegalia senegal and Vachellia seyal, used in the food industry as a stabilizer (e.g. in soda, gumdrops and marshmallows) and other purposes including pharmaceuticals, paints and polishes. Full definition →
gum + Arabic; the name was used in Arabic and other Middle Eastern languages since the 9th century (صَمْغ عَرَبِيّ (ṣamḡ ʕarabiyy)), and retained in the languages of Europeans who first acquired it via Arab ports.
Etymology from Wiktionary, CC BY-SA 4.0.