delta

delta — noun

1. a wide, low-lying region near the end of a river, where the water spreads out in

1.nounB1
Definition

a wide, low-lying region near the end of a river, where the water spreads out into many smaller waterways before emptying into the ocean or a lake

Example

The Mekong delta in Vietnam is famous for its floating markets and rice paddies.

proper noun + delta for a specific river-mouth region

After the flood, the river delta expanded several meters further into the sea.

Common collocations
  • river delta
  • the Nile delta
  • the Mekong delta
  • delta plain
  • delta region
  • delta sediment
Synonyms
  • river mouth

    a more general term for where a river meets the sea; a delta is one type of river mouth

  • alluvial plain

    a broader geographic term referring to the flat land built up by river deposits; a delta is a specific kind of alluvial plain at the coast

Antonyms
  • estuary

    a funnel-shaped tidal river mouth, formed by erosion rather than sediment deposition — the opposite geological process

Common Mistakes

The boat sailed into the delta of the river.
The boat sailed into the estuary of the river.
A delta is a landform built from sediment deposits; an estuary is the tidal mouth where fresh and salt water mix.

2. the name of the fourth symbol (Δ, δ) in the Greek alphabet, used in writing mode

2.nounB2
Definition

the name of the fourth symbol (Δ, δ) in the Greek alphabet, used in writing modern and ancient Greek, and as a scientific symbol for change or difference

Example

In physics class, the symbol delta (Δ) represents a change in value.

countable: the symbol delta

Wei practised writing the Greek letter delta during his first language lesson.

collocation: Greek letter delta

Common collocations
  • Greek letter delta
  • capital delta
  • lowercase delta
  • delta symbol
  • delta (Δ) means change

Word family

  • deltaic
    adjectiveC1

Synonym discussion

Sense: noun/1

Delta, estuary, and river mouth all describe where a river meets the sea, but each refers to a different landform. A delta is a low, flat area built from sediment deposited by the river as it slows down — think of the Nile or Mekong deltas. An estuary is a funnel-shaped tidal mouth where the river widens and salt water mixes with fresh water, typically formed by erosion, not deposition. River mouth is a general, non-technical term for any point where a river ends. Alluvial plain is broader — any flat land created by river deposits over time, not only at the coast. For example: 'The ship entered the estuary of the Thames' (tidal mixing) vs. 'The delta of the Mississippi extends far into the Gulf of Mexico' (sediment buildup).

delta ↗estuaryriver mouthalluvial plain

Common collocations

Nouns

  • delta region
  • delta plain
  • delta sediment
  • delta ecosystem
  • delta formation

Phrases

  • at the mouth of the delta
  • the delta of the [river]

Prepositions

  • in the delta
  • of the delta
  • across the delta
  • into the delta

Etymology

GreekLatinEnglish

The word delta comes from the Greek letter delta (Δ), which has a triangular shape. The ancient Greek historian Herodotus used the term to describe the triangular landform at the mouth of the Nile River because its shape resembled the Greek letter. Over time, the word came to refer to any river-mouth landform with that same fan-like shape.