Sorrel, also called common sorrel or garden sorrel, is a perennial herbaceous plant in the family Polygonaceae. Other names for sorrel include spinach dock and narrow-leaved dock.

The Polygonaceae are a family of flowering plants known informally as the knotweed family or smartweed—buckwheat family in the United States. The name is based on the genus Polygonum, and was first used by Antoine Laurent de Jussieu in 1789 in his book, Genera Plantarum. The name may refer to the many swollen nodes the stems of some species have, being derived from Greek [poly meaning 'many' and gony meaning 'knee' or 'joint']. Alternatively, it may have a different origin, meaning 'many seeds'.