Definition of "Acacia"

(sensu stricto) A taxonomic genus within the family Leguminosae – mostly thornless Australasian shrubs and trees.  examples

(sensu lato, superseded) A genus that included all the genera now included in tribe Acacieae.  examples

An epithet in a botanical name at the rank between species and genus, a name which applies to a section of the genus Acacia.  examples