seaweed

IPA/ˈsiːwiːd/
KK[sˈiwˌid]IPA/ˈsiːwiːd/

seaweed — noun

1. A living thing that lives in the ocean and along the shore. Seaweed grows in dif

1.nounA2
Definition

A living thing that lives in the ocean and along the shore. Seaweed grows in different colors, including green, brown, and red. It does not have stems or flowers like plants on land.

Example

Cole found thick brown seaweed growing on the rocks near the shore.

collocation: brown seaweed

After high tide, the beach was covered in wet seaweed that smelled like the ocean.

Common collocations
  • brown seaweed
  • green seaweed
  • red seaweed
  • a bed of seaweed
  • a patch of seaweed
Synonyms
  • algae

    a broader scientific term that includes seaweed as well as microscopic aquatic plants

  • kelp

    a specific type of large brown seaweed that grows in thick underwater forests

  • marine plant

    a more general term for any plant that grows in the ocean, not limited to algae

Usage Note

Seaweed is most often used as an uncountable noun (e.g., 'There was seaweed all over the beach'). When talking about different types, it can be countable (e.g., 'Many seaweeds grow in tropical waters').

Common Mistakes

There are seaweeds on the beach.' (when referring to general seaweed)
There is seaweed on the beach.
Use the uncountable form when talking about seaweed in general.

2. Seaweed that has been collected from the ocean and prepared for use in food, far

2.nounB1
Definition

Seaweed that has been collected from the ocean and prepared for use in food, farming, or beauty products.

Example

Alessia used dried seaweed to make a soup with tofu and green onions.

collocation: dried seaweed

Farmers near the coast add seaweed to the soil to help their crops grow better.

Common collocations
  • dried seaweed
  • edible seaweed
  • seaweed extract
  • seaweed fertilizer
  • seaweed salad
  • seaweed soup
Synonyms
  • nori

    a specific type of dried seaweed used in Japanese cooking, especially for sushi rolls

  • wakame

    a specific type of edible seaweed often used in soups and salads

Usage Note

In this sense, seaweed is always uncountable. It refers to processed or packaged seaweed used as an ingredient (e.g., 'This salad contains seaweed') rather than the living plant. Distinguish from sense 1 (SEA PLANTS), where seaweed refers to the living organism in its natural habitat.

Common Mistakes

I bought two seaweeds from the store.
I bought two packages of seaweed from the store.
Seaweed is uncountable; use a measure word like 'package of' or 'bag of' to quantify it.

Word family

  • sea
    nounA1
  • weedy
    adjectiveC1

Synonym discussion

Sense: noun/1

Algae is the broadest of these terms and is used in biology to refer to a large group of aquatic organisms that make their own food through photosynthesis. Seaweed refers specifically to the larger, visible forms of marine algae that people commonly encounter on beaches or in the ocean. Kelp is a subset of large brown seaweed that grows in dense underwater forests, while marine plant is a general, non-scientific term for any plant-like organism living in salt water. For everyday use, 'seaweed' is the most natural word: you would say 'The beach was covered in seaweed,' not 'The beach was covered in algae.' Use 'kelp' only when referring to the tall, brown variety found in cold waters, and 'algae' for scientific or aquarium contexts.

algae ↗kelp ↗marine plant

Common collocations

Nouns

  • dried seaweed
  • seaweed salad
  • seaweed soup
  • seaweed extract

Phrases

  • a bed of seaweed
  • a patch of seaweed
  • a strand of seaweed
  • piles of seaweed

Etymology

Old EnglishEnglish

Seaweed is a compound word formed from 'sea' (the saltwater ocean) and 'weed' (a wild plant, especially one that grows abundantly). The word has been used in English since the late 1500s to describe plants growing in the sea, and it was formed by combining two very old English words — 'sea' comes from Old English 'sǣ,' and 'weed' comes from Old English 'wēod.'