1. any of various aquatic plants that grow submerged or floating in water

Examples

• The pond was choked with waterweed that needed to be cleared.
• Fish often hide among the waterweed near the shore.
• The aquarium’s waterweed provides oxygen for the tropical fish.
• Dense waterweed can make swimming difficult in natural lakes.
• The botanist studied different species of waterweed in the marsh.
• Waterweed helps prevent erosion along the riverbank.