delta

1 of 4

noun

del·​ta ˈdel-tə How to pronounce delta (audio)
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 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
What else is going on A decision to reduce water flows in California’s delta sparked a debate over an imperiled fish. Ryan Fonseca, Los Angeles Times, 3 Oct. 2024 But the river’s final 106 kilometers flow through Mexico to a delta along the Gulf of Baja California. Byroberto González, science.org, 14 Aug. 2024 The Perseverance team noticed and targeted the rock in late June as the rover was trundling across the northern slope of Neretva Vallis, a half-kilometer-wide channel carved out eons ago by a river rushing into Jezero Crater, which once held a large lake and delta system. Lee Billings, Scientific American, 26 July 2024 In the delta era, the rate of long COVID among the unvaccinated fell slightly to 9.51 out of 100. Beth Mole, Ars Technica, 18 July 2024 See all Example Sentences for delta 

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'delta.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

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

Time Traveler
The first known use of delta was in the 12th century

Dictionary Entries Near delta

Cite this Entry

“Delta.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/delta. Accessed 31 Oct. 2024.

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 How to pronounce delta (audio)
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
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 How to pronounce Delta (audio)
1
municipality south and southeast of Vancouver in southwestern British Columbia, Canada population 99,863
2

More from Merriam-Webster on delta

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