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

Since the property changed hands, its sole restaurant, 18 Restaurant & Bar, has become more markedly gourmet with fare like scallops dusted with seaweed crumbs, smoked trout under cucumber and vermouth relish, and venison enlivened by juniper jus and pickled berries. —Arati Menon, Condé Nast Traveler, 18 Dec. 2024

However, in popular tourist areas along the Yucatán coast like Cancun, Playa Del Carmen, Tulum, and others, the beach may become piled high with sargassum, a type of seaweed that can also make the water unswimmable. —Emily Hochberg, Travel + Leisure, 18 Dec. 2024

Dolphins can often be spotted playing with blades of seaweed or seagrass, or even with the sand on the ocean floor. —Scott Travers, Forbes, 17 Dec. 2024

The blend of seaweed and hyaluronic acid leaves your skin plump and bouncy in no time. —Jessica Copeland, Rolling Stone, 16 Dec. 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)