seaweed

noun

sea·​weed ˈsē-ˌwēd 

1

plural seaweeds : any of various aquatic and chiefly marine brown, red, or green algae (such as rockweed, gulfweed, and kelp) that often grow in masses, typically have leaflike blades (see blade entry 1 sense 2e), are usually anchored to a solid substrate (such as a rock) by holdfasts (see holdfast sense 2a), and include some (such as dulse, laver, and sea lettuce) that are used as food

… many seaweeds have floats called pneumatocysts, filled with oxygen or carbon dioxide.

—Michael Le Page

The word seaweed is broad and refers generally to marine macroalgae, which are algae living in salt or brackish water and visible to the eye.

—Elyse Inamine

2

: a mass or growth of seaweeds

… soft crabs were easily visible in the seaweed, because the water was crystal clear then.

—Keith Walters

3

: harvested seaweed or seaweed parts used especially as food, fertilizer, and in cosmetics

… sushi rolls wrapped in thin sheets of dried seaweed …

—Jane Snow

Examples of seaweed in a Sentence

Recent Examples on the Web

It's believed that one of the reasons behind this is the Japanese diet, which is filled with nutrient-rich foods like seaweed, matcha tea, and tofu. —Veronica Cristino, Vogue, 7 Dec. 2024

Sustainable harvesting practices are crucial, as demonstrated by Iceland, where regulations maintain the health of the seaweed’s native population. —Boutayna Chokrane, WIRED, 6 Dec. 2024

What to try: Laphroaig 10 Year is an Islay staple, known for its powerful aroma of smoke, seaweed, and medicinal notes. —Emily Price, Forbes, 2 Dec. 2024

Some of the most popular types include: Mannitol: Naturally found in pineapples, olives, asparagus, sweet potatoes, and yams and extracted from seaweed when used as an ingredient in food. —Jamie Johnson, Verywell Health, 27 Nov. 2024

Word History

First Known Use

1577, in the meaning defined at sense 1a

Kids Definition

seaweed

noun

sea·​weed -ˌwēd 

: a plant growing in the sea

especially : a marine alga (as a kelp)