del·​ta | \ ˈdel-tə How to pronounce delta (audio) \

Definition of delta

 (Entry 1 of 5)

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


adjective (1)

Definition of delta (Entry 2 of 5)

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


communications code word

Definition of Delta (Entry 3 of 5)

used as a code word for the letter d


adjective (2)

Definition of Delta (Entry 4 of 5)

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


geographical name
Del·​ta | \ ˈdel-tə How to pronounce Delta (audio) \

Definition of Delta (Entry 5 of 5)

1 municipality south and southeast of Vancouver in southwestern British Columbia, Canada population 99,863
2 see delta, the

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Other Words from delta


deltaic \ del-​ˈtā-​ik How to pronounce deltaic (audio) \ adjective

Examples of delta in a Sentence

Recent Examples on the Web: Noun

Water drawn from the rivers and spread across their deltas allows the lowland farmers to raise two crops a year, sometimes three. The Economist, "The South Asian monsoon, past, present and future," 27 June 2019 The pacts were aimed at allowing greater flexibility in how to protect endangered species and divert water from the delta. Phil Willon, San Diego Union-Tribune, "Newsom plans to veto bill that would have blocked Trump’s rollback of endangered species protections," 14 Sep. 2019 The pacts were aimed at allowing greater flexibility in how to protect endangered species and divert water from the delta. Phil Willon, Los Angeles Times, "California lawmakers vote to block Trump’s environmental rollbacks, defying Newsom," 14 Sep. 2019 Taking cues from the darkest corners of the Americana pantheon, Muddy Ruckus writes music with a sort of evil edge usually reserved for swampy deltas along various Mississippi River pit stops. Chip Mccabe,, "One can’t-miss band for every day at The Big E," 3 Sep. 2019 The fate of the smelt itself is a distraction; the real issue is the fate of the delta. Michael Hiltzik, Los Angeles Times, "Column: Right-wingers again demonize the tiny delta smelt to protect Big Agriculture," 12 Aug. 2019 In the Yazoo Basin, a section of the delta where farming is the linchpin of the economy, people are still struggling to cope with a flood that seems forgotten by nearly everyone outside the disaster zone. Rory Doyle, New York Times, "Where Floods of ‘Biblical Proportion’ Drowned Towns and Farms," 30 July 2019 The ship was then taken into delta waters and burned to avoid detection. Washington Post, "Last slave ship: Alabama files federal claim of ownership," 29 July 2019 Satellite pictures show their lush paddy fields of the delta as emerald patches on the brown scrub of the Coromandel coast and the land behind. The Economist, "The South Asian monsoon, past, present and future," 27 June 2019

Recent Examples on the Web: Adjective

Fisheries experts and environmentalists say the tunnels will devastate delta fish by depriving them of the most critical ingredient in their survival — freshwater. Peter Fimrite, San Francisco Chronicle, "California’s two-tunnel Delta project is back on track with SoCal water district’s vote," 10 Apr. 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'delta.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of delta


13th 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

History and Etymology for delta

Noun and Adjective (1)

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

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Dictionary Entries near delta






delta agent

delta connection

Statistics for delta

Last Updated

12 Oct 2019

Look-up Popularity

Time Traveler for delta

The first known use of delta was in the 13th century

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More Definitions for delta



Financial Definition of delta

What It Is

Delta is the ratio comparing the change in price of an underlying asset to the change in price of a derivative. It is one of the four main statistics, known as "Greeks," used to analyze derivatives.

How It Works

Let's assume you own a call option on Company XYZ stock. If the price of Company XYZ stock increased by $1.00 and the call option increased by $0.80 in the same time period, then the delta is 0.80 ($0.80/$1.00).

The definition of delta on InvestingAnswersPut options work inversely. Since put options lose value as the underlying security increases, delta is a negative number. If a stock increases $1.00, and the put price decreases $0.50, then the put option has a delta of -0.50. Deltas aren't constant and change according to fluctuations in the underlying stock's price, time left on the derivative until expiration, and volatility in the underlying stock.

Why It Matters

Delta allows derivatives traders to understand what sort of risk/return they can expect from an investment. For instance, if they believe a stock will increase $2.00 per share in the near future, they can buy a call option on the stock. By using the delta calculation, the investor can calculate their potential gain from the stock's move -- important information to know before taking a risk.

Source: Investing Answers



English Language Learners Definition of delta

: the fourth letter of the Greek alphabet
: a piece of land shaped like a triangle that is formed when a river splits into smaller rivers before it flows into an ocean
US : an area of low land along the Mississippi River that is mainly in the state of Mississippi


del·​ta | \ ˈdel-tə How to pronounce delta (audio) \

Kids Definition of delta

: a piece of land in the shape of a triangle or fan made by deposits of mud and sand at the mouth of a river

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del·​ta | \ ˈdel-tə How to pronounce delta (audio) \

Medical Definition of delta

 (Entry 1 of 2)

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


variants: or ƍ-

Medical Definition of delta (Entry 2 of 2)

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

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More from Merriam-Webster on delta

Spanish Central: Translation of delta

Nglish: Translation of delta for Spanish Speakers

Britannica English: Translation of delta for Arabic Speakers Encyclopedia article about delta

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