plural deltas
1
: the 4th letter of the Greek alphabet see Alphabet Table
2
: something shaped like a capital Greek 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)
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
Suresh V. Kuchipudi
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 4communications code word
—used as a code word for the letter d
: of, relating to, or characteristic of the The Delta region of Mississippi
Examples of delta in a Sentence
Recent Examples on the Web
Don Muir, Forbes, 3 Nov. 2024
However, environmentalists are pushing back against the plan over concerns about environmental impacts, such as threatening endangered fish species living in the delta should the proposal come to fruition.
—Nina Turner, Newsweek, 30 Oct. 2024
Last week, Mark and I returned to the delta to revisit those restoration areas and to interview people who gathered to celebrate the pulse flow's 10-year anniversary.
—Shaun McKinnon, The Arizona Republic, 28 Oct. 2024
The delta between a solid season and great season is likely determined by Bowman cutting down turnovers and reaching a completion rate in the mid-60s.
—Stewart Mandel, The Athletic, 26 Aug. 2024
See all Example Sentences for delta 
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Noun
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Running a complex private debt deal takes a lot of man power, but the delta of hours between a $50M process and a $500M process actually isn’t that wide.
—Don Muir, Forbes, 3 Nov. 2024
However, environmentalists are pushing back against the plan over concerns about environmental impacts, such as threatening endangered fish species living in the delta should the proposal come to fruition.
—Nina Turner, Newsweek, 30 Oct. 2024
Last week, Mark and I returned to the delta to revisit those restoration areas and to interview people who gathered to celebrate the pulse flow's 10-year anniversary.
—Shaun McKinnon, The Arizona Republic, 28 Oct. 2024
The delta between a solid season and great season is likely determined by Bowman cutting down turnovers and reaching a completion rate in the mid-60s.
—Stewart Mandel, The Athletic, 26 Aug. 2024
See all Example Sentences for delta
Dictionary Entries Near delta
Cite this Entry
“Delta.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/delta. Accessed 29 Nov. 2024.
Copy CitationMedical 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
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
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