Acalypha rhomboidea is an annual plant in the spurge family, Euphorbiaceae. It is known by the common names common three-seeded mercury, rhombic three-seeded-mercury, rhomboid mercury, copperleaf, rhombic copper-leaf, three-seeded-mercury, ricinelle rhomboide, and diamond threeseed mercury. Synonyms include Acalypha urticifolia Raf., Acalypha virginica L. forma intermedia Millsp., Acalypha virginica L. var. rhombifolia Riddell, Acalypha virginica L. var. rhomboidea (Raf.) Cooperr..

The species name rhomboidea means "diamond-shaped", and describes the leaves.