Pondweed \Pond"weed`\, n. (Bot.) Any aquatic plant of the genus {Potamogeton}, of which many species are found in ponds or slow-moving rivers. {Choke pondweed}, an American water weed ({Anarcharis, or Elodea, Canadensis}.) See {Anacharis}. {Horned pondweed}, the {Zannichellia palustris}, a slender, branching aquatic plant, having pointed nutlets.