sea

American  

[see] / si /

noun

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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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

That may sound barmy, what with all the ships being deployed in and around the Arabian Sea for weeks already, and reports that the military is running out of munitions.

From Salon • May 12, 2026

Djibouti, at the mouth of the Red Sea, now hosts France's last remaining operational military base in Africa.

From BBC • May 12, 2026

While Saudi Arabia’s exports via the Red Sea and occasional tanker passage through the Strait of Hormuz have eased some price pressures, “we feel that oil values are still mispriced to the low side.”

From The Wall Street Journal • May 11, 2026

The rerouting of shipping around South Africa and away from the Red Sea and Suez Canal since late 2023 has "substantially increased" the chances of ship strikes, they said in new research.

From Barron's • May 11, 2026

The ship that she’s talking about is a vessel that her project discovered more than a mile below the surface in the Black Sea, off the coast of Bulgaria.

From "Shipwrecked!" by Martin W. Sandler

Related Words

• expanse
• lake
• ocean
• pond
• surf