lagoon

lagoon — noun

1. a relatively shallow body of salt water along a coastline that is partly or comp

1.nounB1
Definition

a relatively shallow body of salt water along a coastline that is partly or completely cut off from the open ocean by a natural barrier such as a coral reef, a sandbank, or a strip of land, creating a calm sheltered area.

Example

The turquoise lagoon behind the coral reef was full of colourful fish.

coral reef lagoon — noun-noun compound for natural settings

Layla and her family went swimming in the warm lagoon every afternoon.

Common collocations
  • coral lagoon
  • tropical lagoon
  • coastal lagoon
  • shallow lagoon
  • turquoise lagoon
  • lagoon water
  • lagoon reef
  • lagoon ecosystem
Synonyms
  • inlet

    a narrow body of water that reaches into the land from the sea, but is not separated by a barrier reef

  • bay

    a wide curve of coastline that is open to the sea on one side, unlike a lagoon

  • sound

    a large sea inlet that is deeper and wider than a lagoon

Antonyms
  • open ocean

    the vast body of sea water beyond the coastline, not sheltered by any barrier

Grammar Patterns

adjective + lagoon

lagoon + noun (e.g. lagoon water)

Usage Note

Frequently used in travel and geography writing. Distinguish from 'bay', which has a wider opening to the sea, and 'inlet', which is a narrow channel connecting directly to the ocean.

Common Mistakes

We went swimming in the lagoon next to the river.
We went swimming in the lagoon behind the coral reef.
A lagoon is separated from the sea by a natural barrier, not connected to a freshwater river.
The children built sandcastles on the lagoon.
The children built sandcastles on the beach next to the lagoon.
A lagoon is a body of water, not a landform.

2. a man-made shallow basin or pond, constructed to hold and process liquid waste s

2.nounB2
Definition

a man-made shallow basin or pond, constructed to hold and process liquid waste such as sewage or industrial water, often as part of a treatment system before the water is released into the environment.

Example

The town built a large waste lagoon behind the factory to hold industrial water.

waste lagoon — noun-noun compound for artificial basins

Mert tested the water in the treatment lagoon before it went into the river.

treatment lagoon — noun-noun compound in environmental contexts

Common collocations
  • sewage lagoon
  • waste lagoon
  • treatment lagoon
  • aeration lagoon
  • lagoon system
  • lagoon overflow
  • wastewater lagoon
  • industrial lagoon
Synonyms
  • settling pond

    a pond where solid waste particles are allowed to sink to the bottom, a type of treatment lagoon

  • treatment pond

    a general term for any artificial basin used in wastewater processing

Grammar Patterns

noun + lagoon (e.g. sewage lagoon)

adjective + lagoon (e.g. treatment lagoon)

Usage Note

Common in environmental engineering and farming contexts. Almost always used in compounds like 'sewage lagoon', 'waste lagoon', or 'treatment lagoon'. This sense does NOT describe a natural or recreational body of water.

Common Mistakes

The children played in the waste lagoon behind the school.
The waste lagoon is fenced off because the water is unsafe.
Artificial waste lagoons are hazardous and never used for recreation.
A beautiful lagoon in the park had ducks swimming in it.
A sewage lagoon is used to treat waste, not for wildlife or leisure.
Mixing the natural and industrial senses confuses the meaning.

Word family

  • lagoonal
    adjectiveC1

Synonym discussion

Sense: noun/1

Lagoon, bay, inlet, sound, and cove all describe coastal water features, but differ in how they connect to the sea. A lagoon is partly or fully separated from the open ocean by a natural barrier like a reef or sandbank — it is the most sheltered of the group. A bay is a wide, open curve of coastline that remains connected to the sea on one side, such as San Francisco Bay. An inlet is a narrow channel that leads from the sea into the land, providing a passage for boats — it is longer and narrower than a lagoon. A sound is a large, deep inlet that often connects two larger bodies of water, like Puget Sound. A cove is a small, rounded bay with a narrow entrance, usually sheltered by cliffs on both sides. For everyday travel contexts: 'We swam in a warm lagoon behind the reef' vs. 'We sailed into a quiet cove for lunch.'

lagoon ↗bay ↗inletsound ↗cove ↗

Common collocations

Nouns

  • lagoon water
  • lagoon system
  • lagoon ecosystem

Phrases

  • the edge of the lagoon
  • the mouth of the lagoon
  • the surface of the lagoon

Prepositions

  • in a lagoon
  • across the lagoon
  • into the lagoon
  • around the lagoon
  • by the lagoon
  • behind the lagoon

Etymology

LatinItalianEnglish

The word 'lagoon' entered English in the 17th century from Italian 'laguna', which described the shallow, marshy waters around Venice. Italian took it from Latin 'lacuna', meaning a pool or a hollow space, which itself came from 'lacus' (lake). The geographical meaning of a coastal saltwater body separated by a reef developed from the distinctive landscape of the Venetian Lagoon.