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
Services on offer include a seaweed leaf wrap ($350 for 90 minutes) to detoxify, a deep muscle melter massage ($225 for an hour) to release any tension, and a skin renewal facial ($230 for 60 minutes).
—Nicole Hoey, Robb Report, 21 May 2025
Emerging sustainable options to plastic packaging are made with mushrooms, seaweed, starch and wheat straw
0:00
1:18
Consumer packaging dumps 19 million metric tons of plastic waste into the environment each year, according to the nonprofit advocacy group Beyond Plastics.
—Adam Stone, USA Today, 16 May 2025
The formula is made with over 100 billion live microbes per gallon in addition to minerals, essential nutrients, humic acid, and seaweed extract.
—Kate Puhala, Better Homes & Gardens, 9 May 2025
At another, an employee cuts and rolls fish into a seaweed wrap.
—Jenna Thompson, Kansas City Star, 14 May 2025
See All Example Sentences for seaweed
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Nicole Hoey, Robb Report, 21 May 2025
Emerging sustainable options to plastic packaging are made with mushrooms, seaweed, starch and wheat straw
0:00
1:18
Consumer packaging dumps 19 million metric tons of plastic waste into the environment each year, according to the nonprofit advocacy group Beyond Plastics.
—Adam Stone, USA Today, 16 May 2025
The formula is made with over 100 billion live microbes per gallon in addition to minerals, essential nutrients, humic acid, and seaweed extract.
—Kate Puhala, Better Homes & Gardens, 9 May 2025
At another, an employee cuts and rolls fish into a seaweed wrap.
—Jenna Thompson, Kansas City Star, 14 May 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 10 Jun. 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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