ocean

noun

ˈō-shən 

plural oceans

often attributive

1

a

: the whole body of salt water that covers nearly three fourths of the surface of the earth

The ocean covers most of our planet, regulates our weather and climate, absorbs vast amounts of carbon dioxide, provides most of our oxygen, and feeds much of the human population.

—National Oceanic and Atmospheric Administration

b

: any of the large bodies of water into which the great ocean is divided

the oceans of the world

2

: a very large or unlimited quantity or expanse

Could have made oceans of money.

—James Joyce

He would have oceans of time for his ride.

—P. G. Wodehouse

Jutting from an ocean of prairie, they [the Sangre de Cristo mountains] run north-south like an iguana spine …

—Skiing

Synonyms

• sea

Examples of ocean in a Sentence

We've sailed across hundreds of miles of ocean.

the Pacific and Indian oceans

Recent Examples on the Web

But warming ocean temperatures, rising sea levels, disease and human activity, such as pollution, have severely degraded Florida's reefs, according to the Florida Keys National Marine Sanctuary. —Julia Jacobo, ABC News, 1 Oct. 2025

Some models suggest that K2-18b is a hycean world — an ocean planet with a thick atmosphere of hydrogen — and the signature of dimethyl sulfide was detected by the James Webb Space Telescope. —Keith Cooper, Space.com, 1 Oct. 2025

About 300 to 400 linear feet (91 to 122 meters) of a coastal slope sloughed off, falling about 50 to 60 feet (15 to 18 meters) toward the ocean, according to the Los Angeles County Fire Department. —Jim Edwards, Fortune, 1 Oct. 2025

In North Carolina’s Outer Banks, at least five homes collapsed into the ocean, the National Park Service said. —Alexandra Banner, CNN Money, 1 Oct. 2025

Word History

Etymology

Middle English occean "the sea flowing around the land mass of the known world," borrowed from Anglo-French, borrowed from Latin Ōceanus, borrowed from Greek Ōkeanós, probably of pre-Greek substratal origin

Note: Preserved variants of Greek Ōkeanós, as Ōgḗn, Ōgenós, Ōgēnós, may indicate that the velar stop, whatever its original voicing, was palatalized (hence *ūkʸān-?)—strongly suggesting non-Indo-European origin. Old attempts to find an Indo-European origin (as a comparison with Sanskrit ā-śayāna- "lying on") are unconvincing.

First Known Use

14th century, in the meaning defined at sense 1a

Phrases Containing ocean

• a drop in the ocean
• inter-ocean
• mid-ocean ridge
• ocean perch
• ocean sunfish
• open ocean

Rhymes for ocean

• lotion
• notion
• potion
• commotion
• demotion
• devotion
• emotion
• laotian
• promotion
• locomotion

Kids Definition

ocean

noun

ˈō-shən 

1

: the whole body of salt water that covers nearly three fourths of the surface of the earth

2

: one of the large bodies of water into which the ocean is divided

oceanic

ˌō-shē-ˈan-ik

adjective