delta

1 of 4

noun

del·​ta ˈdel-tə 

plural deltas

1

: the 4th letter of the Greek alphabet see Alphabet Table

2

: something shaped like a capital Greek delta

especially, geology : the alluvial deposit at the mouth of a river

the Mississippi Delta

3

mathematics : an increment of a variable

—symbol Δ

4

: delta wave

During deep sleep, the brain operates in delta wave frequency. But it's difficult to go from beta to theta then delta without first switching down to a relaxed alpha state.

—Daily Mail (London)

5

or less commonly Delta : delta variant

As SARS-CoV-2 continues to spread among humans, natural selection and adaptation will result in more variants that could plausibly be more transmissible than delta.

—Suresh V. Kuchipudi

deltaic

del-ˈtā-ik 

adjective

delta

2 of 4

adjective (1)

chemistry

: fourth in position in the structure of an organic (see organic entry 1 sense 1b(2)) molecule from a particular group or atom

—symbol δ

Delta

3 of 4

communications code word

—used as a code word for the letter d

Delta

4 of 4

adjective (2)

: of, relating to, or characteristic of the The Delta region of Mississippi

Examples of delta in a Sentence

Recent Examples on the Web

Noun

Similarly, if a U.S. health tech startup is looking to enter the Dutch market, partnering with local healthcare providers and tech hubs like in Amsterdam's startup delta could help a startup gain crucial market insights and build credibility in the Netherlands. —Alexander Storozhuk, Forbes, 12 Sep. 2024

The current infrastructure, which was built in the 1960s, includes massive pumps that draw water from the delta and send it flowing into the California Aqueduct. —Ian James, Los Angeles Times, 31 July 2024

But its location in the heart of the delta, situated between the Moremi Game Reserve and Gomoti Plains, offers that sweet spot between creatures and creature comforts. —Lisa Grainger, Condé Nast Traveler, 9 July 2024

For generations, communities in Satkhira adapted to the ebb and flow that defines the delta ecosystem. —Mahadi Al Hasnat, Vox, 30 May 2024

Word History

Etymology

Noun and Adjective (1)

Middle English deltha, from Greek delta, of Semitic origin; akin to Hebrew dāleth daleth

First Known Use

Noun

12th century, in the meaning defined at sense 1

Adjective (1)

circa 1929, in the meaning defined above

Communications Code Word

1952, in the meaning defined above

Adjective (2)

1859, in the meaning defined above

Phrases Containing delta

• delta agent
• delta hepatitis
• delta ray
• delta variant
• delta virus
• delta wave
• delta wing
• hepatitis delta virus
• Kronecker delta

Kids Definition

delta

noun

del·​ta

ˈdel-tə

1

: the 4th letter of the Greek alphabet

—Δ or ƍ

2

: something shaped like a capital Δ

especially : the triangular or fan-shaped piece of land made by deposits of mud and sand at the mouth of a river

deltaic

del-ˈtā-ik

adjective

Medical Definition

delta

1 of 2 noun

del·​ta ˈdel-tə 

1

: the fourth letter of the Greek alphabet

—symbol Δ or ƍ

2

: any of various things felt to resemble a capital Δ

especially : the triangular terminus of a pattern in a fingerprint formed either by bifurcation of a ridge or by divergence of two ridges that are parallel beyond it

3

: delta wave

4

also Delta : delta variant

delta

2 of 2 adjective

variants or ƍ-

1

: of or relating to one of four or more closely related chemical substances

the delta chain of fetal hemoglobin

ƍ-yohimbine

—used somewhat arbitrarily to specify ordinal relationship or a particular physical form and especially one that is allotropic, isomeric, or stereoisomeric (as in ƍ-benzene hexachloride)

2

: fourth in position in the structure of an organic molecule from a particular group or atom

also : having a structure characterized by such a position

ƍ-hydroxy acids

ƍ-lactones

Geographical Definition

Delta

geographical name

Del·​ta ˈdel-tə 

1

municipality south and southeast of Vancouver in southwestern British Columbia, Canada population 99,863

2

see delta, the