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
Michael Le PageThe 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
Elyse Inamine2
: a mass or growth of seaweeds
… soft crabs were easily visible in the seaweed, because the water was crystal clear then.—Keith Walters
Keith Walters3
: harvested seaweed or seaweed parts used especially as food, fertilizer, and in cosmetics
… sushi rolls wrapped in thin sheets of dried seaweed …—Jane Snow
Jane SnowExamples of seaweed in a Sentence
Recent Examples on the Web
In coral reefs, for example, the presence of sharks alters how and where herbivorous fish feed, which in turn affects seaweed growth and habitat structure.
—Melissa Cristina Márquez, Forbes.com, 8 Apr. 2025
Sun Sentinel Record-breaking seaweed in Atlantic could mean stinky beaches in South Florida
Levels of floating seaweed mats, known as sargassum, have skyrocketed in the Atlantic Ocean in the past month, with the total amount breaking the record for March.
—South Florida Sun Sentinel, Sun Sentinel, 2 Apr. 2025
The government has promoted seaweed farming as a source of income, while overseas conservation groups have offered cash to end the hunts.
—Prianka Srinivasan Matthew Abbott, New York Times, 26 Mar. 2025
Elodie Bost Spot prawn Photo : Elodie Bost Turbot
Photo : Elodie Bost
Squab
Photo : Elodie Bost
Beef with mushrooms and seaweed
Photo : Elodie Bost
Eric Bost
Photo : Elodie Bost
John Resnick
Jeremy Repanich
Jeremy Repanich is Robb Report's culinary editor.
—Jeremy Repanich, Robb Report, 26 Mar. 2025
See All Example Sentences for seaweed
Examples are automatically compiled from online sources to
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Melissa Cristina Márquez, Forbes.com, 8 Apr. 2025
Sun Sentinel Record-breaking seaweed in Atlantic could mean stinky beaches in South Florida
Levels of floating seaweed mats, known as sargassum, have skyrocketed in the Atlantic Ocean in the past month, with the total amount breaking the record for March.
—South Florida Sun Sentinel, Sun Sentinel, 2 Apr. 2025
The government has promoted seaweed farming as a source of income, while overseas conservation groups have offered cash to end the hunts.
—Prianka Srinivasan Matthew Abbott, New York Times, 26 Mar. 2025
Elodie Bost Spot prawn Photo : Elodie Bost Turbot
Photo : Elodie Bost
Squab
Photo : Elodie Bost
Beef with mushrooms and seaweed
Photo : Elodie Bost
Eric Bost
Photo : Elodie Bost
John Resnick
Jeremy Repanich
Jeremy Repanich is Robb Report's culinary editor.
—Jeremy Repanich, Robb Report, 26 Mar. 2025
See All Example Sentences for seaweed
Cite this Entry
“Seaweed.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/seaweed. Accessed 22 Apr. 2025.
Copy CitationKids Definition
seaweed
noun
sea·weed
-ˌwēd 
: a plant growing in the sea
especially
: a marine alga (as a kelp)
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Merriam-Webster unabridged
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