Originally: any of several kinds of aquatic plant (not identified). Later: specifically (Potamogeton) a cosmopolitan genus of aquatic plants with submerged and sometimes floating leaves (family Potamogetonaceae); (also potamogeton) any of various plants of this genus; a pondweed.
Valid publication of the genus name: Linnaeus Species Plantarum (1753) 126, after earlier use by Tournefort (1700).
Early 17th century; earliest use found in Philemon Holland (1552–1637), translator. From post-classical Latin potamogeton, variant (e.g. in 16th-cent. editions of Pliny) of classical Latin potamogītōn (Pliny) from Hellenistic Greek ποταμογείτων pondweed from ancient Greek ποταμός river + γείτων neighbour.