sea

American  

[see] / si /

noun

• seas
  plural

1. the salt waters that cover the greater part of the earth's surface.

2. a division of these waters, of considerable extent, more or less definitely marked off by land boundaries.

   the North Sea.

3. one of the seven seas; ocean.

4. a large lake or landlocked body of water.

5. the degree or amount of turbulence of the ocean or other body of water, as caused by the wind.

6. the waves.

7. a large wave.

   The heavy seas almost drowned us.

8. a widely extended, copious, or overwhelming quantity.

   a sea of faces; a sea of troubles.

   Synonyms:

   mass, abundance, host, multitude

9. the work, travel, and shipboard life of a sailor.

   The sea is a hard life but a rewarding one.

10. Astronomy. mare.

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adjective

1. of, relating to, or adapted for use at sea.

idioms

1. at sea, Also

   1. on the ocean.

   2. perplexed; uncertain.

      completely at sea as to how to answer the question.

2. go to sea,

   1. to set out on a voyage.

   2. to embark on a nautical career.

3. half seas over, partly or completely drunk: Also

   They came home at dawn, looking half seas over.

4. put to sea, to embark on a sea voyage: Also put out to sea.

   The expedition is nearly ready to put to sea.

5. follow the sea, to pursue a nautical career.

   Many boys then dreamed of following the sea.

sea British  

/ siː /

noun

1. 1. the mass of salt water on the earth's surface as differentiated from the land

   2. ( as modifier )

      sea air

2. (capital when part of place name)

   1. one of the smaller areas of ocean

      the Irish Sea

   2. a large inland area of water

      the Caspian Sea

3. turbulence or swell, esp of considerable size

   heavy seas

4. (capital when part of a name) astronomy any of many huge dry plains on the surface of the moon See also mare 2

5. anything resembling the sea in size or apparent limitlessness

6. the life or career of a sailor (esp in the phrase follow the sea )

7. 1. on the ocean

   2. in a state of confusion

8. to become a sailor

9. to embark on a sea voyage

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sea Scientific  

/ sē /

1. The continuous body of salt water that covers most of the Earth's surface.

2. A region of water within an ocean and partly enclosed by land, such as the North Sea.

3. See Note at ocean

4. A large body of either fresh or salt water that is completely enclosed by land, such as the Caspian Sea.

5. Astronomy A mare.

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sea More Idioms  

More idioms and phrases containing sea

• at sea
• between a rock and a hard place (devil and the deep blue sea)
• high seas
• not the only fish in the sea
• put out (to sea)

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Other Word Forms

Noun Inflected Forms

• seas
  plural

Etymology

Origin of sea

First recorded before 900; Middle English see, Old English sǣ; cognate with Dutch zee, German See, Old Norse sær “sea,” Gothic saiws “marsh”

Explanation

A sea is a huge body of salt water, typically a part of the ocean that's near land. Much grander than a lake or river, a sea can appear open and endless when you view it from the shore. The best-known examples of sea include the Mediterranean Sea, Bering Sea, and Caribbean Sea. The word sea can also refer to large waves. If there's a sea warning, it would be wise to reschedule your sailing trip. Sea can be used more figuratively to describe something that seems to be vast in quantity, just like the sea. The audience at your concert might look like an endless sea of people.

Example Sentences

See Examples For:

sea seas

Research is being carried out to find out how a microplastic spillage has affected coastal sea bird populations.

From BBC ● Oct. 7, 2026

Rising sea levels have already largely swamped two of Tuvalu's nine coral atolls -- and scientists fear the entire archipelago could be unliveable by the end of the century.

From Barron's ● Oct. 4, 2026

It said coastal sites were among those facing the greatest climate pressures, including erosion and rising sea levels.

From BBC ● Oct. 4, 2026

Pilots navigating the island also face heavy turbulence, low-lying sea fog, sudden microclimates and strong updrafts and downdrafts that can push a small aircraft off course.

From Los Angeles Times ● Oct. 3, 2026

A pair of gannets flew high over us, going toward the sea.

From "Nory Ryan’s Song" by Patricia Reilly Giff

The South Pacific is among the regions of the world most vulnerable to global warming -- from rising seas jeopardising homes to increasing temperatures causing coral bleaching.

From Barron's ● Oct. 7, 2026

During her breakfast show appearance, Thirlwall said Blue Planet, which focuses on the life of our seas and oceans, was her favourite TV show.

From BBC ● Oct. 6, 2026

The work forms part of a broader investigation into the early history of modern reptile groups and the diversity of reptiles that inhabited Triassic seas.

From Science Daily ● Sep. 29, 2026

Warmer seas help spawn Pacific hurricanes, which have already battered Hawai‘i this year. As I write this, rhyming storms named Polo and Nolo threaten to bring flooding to Hawai‘i and Mexico.

From Slate ● Sep. 28, 2026

When they did not row they bailed, for the seas broke heavy on the ship.

From "A Wizard of Earthsea" by Ursula K. Le Guin

Related Words

• expanse
• lake
• ocean
• pond
• surf