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 largely obscured by seaweed and, from the looks of it, home to a lone Baltic flounder that’s swimming around the base. —Paul Hockenos, Smithsonian Magazine, 10 Sep. 2024

The spread of this seaweed has grown so vast in recent times that it can be seen from space. —Scott Travers, Forbes, 3 Nov. 2024

It’s enriched with a blend of gardenia extract, rosewater, aloe vera, thyme, and even seaweed extract. —Kat Romero, Rolling Stone, 10 Oct. 2024

Today’s replies – tuna casserole, seaweed, pickles submerged in Dr Pepper – are eclipsed by Mr. Thomas’ recipe for freezing a thousand live crickets and then sprinkling them with olive oil and salt before baking. —Patricia Leigh Brown, The Christian Science Monitor, 12 Sep. 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)