Seaweed (noun)

Plants that grow in the ocean, mostly in shallow waters near the shore.

Origin:

From middle english "seaweed", from "sea" + "weed".

Examples:

1. Seaweed is an important source of food and medicine in Asia.
2. The beach was covered in seaweed after the storm.
3. He harvested seaweed for use in his restaurant.
4. She went diving to collect samples of different types of seaweed.
5. The seaweed on the rocks was being tossed around by the waves.