Acacia \a-ca-cia\ as a girl's name is pronounced a-KAY-shah. It is of Greek origin, and the meaning of Acacia is "thorny tree". Name of the flower related to the mimosa. The plant was named in the 16th century with the Latin form "acacia" of Greek "akakia". Biblical: acacia wood was used to build the Arc of the Covenant. Sometimes, Keisha is considered a short form of this name.