Duckweed (noun)

A small, floating aquatic plant that forms dense green mats on the surface of still or slow-moving water bodies.

Origin:

From middle english dokeweede, from duck + weed.

Examples:

1. Duckweed is often considered a nuisance by farmers and landowners due to its ability to clog irrigation ditches.
2. Duckweed provides a habitat for many species of aquatic animals.
3. The pond was covered in a thick layer of duckweed, making it difficult to see the fish below.
4. Duckweed is a type of flowering plant and is a good source of nutrition for ducks and other waterfowl.
5. The scientists are studying the potential use of duckweed as a source of biofuel and animal feed.