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

Definition of delta

 (Entry 1 of 4)

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



Definition of delta (Entry 2 of 4)

: fourth in position in the structure of an organic (see organic entry 1 sense 3b(1)) molecule from a particular group or atom symbol ƍ


communications code word

Definition of Delta (Entry 3 of 4)

used as a code word for the letter d


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

Definition of Delta (Entry 4 of 4)

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

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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

The other major problem is federal regulations, known as biological opinions, that limit the rate at which water in the delta can be pumped to the south of the state. The Editorial Board, WSJ, "Trump’s California Water Relief," 19 Oct. 2018 Its opening will cut travel time across the delta from several hours to just 30 minutes, something China hopes will bind the region together as a major driver of future economic growth. Dake Kang, The Seattle Times, "China opens mega-bridge linking Hong Kong to mainland," 23 Oct. 2018 But freshwater flows into the delta would be rerouted into the tunnels. George Skelton,, "What do Southern Californians really get out of Gov. Jerry Brown's twin tunnels project?," 12 July 2018 The Niger Delta Avengers, a militant group whose aim is to garner more oil revenue for the delta region, has threatened to return to violence if Mr. Buhari wins the election. Neanda Salvaterra, WSJ, "On the Ballot in Nigeria: How to Manage Oil Money," 21 Feb. 2019 Lopez, 20, hitched 800 kilometers from her home in the Orinoco river delta to the Brazilian border five months ago. Fox News, "Pregnant Venezuelan women going to Brazil to give birth," 22 Aug. 2018 Thanks to the ubiquity of Qualcomm chips, there's not a huge speed delta between devices at this price range, but HMD was generous enough to give the Nokia 6.1 a better SoC than the Moto G6's Snapdragon 450. Ron Amadeo, Ars Technica, "Nokia 6.1 Review—The best answer to “What Android phone should I buy?”," 13 July 2018 Anywhere from 10% to 18% of the northern European population have a mutation in the CCR5 gene called delta 32 that prevents most types of HIV from entering the body. Amy Dockser Marcus, WSJ, "Scientists Skeptical About Gene-Edited Baby Experiment," 12 Dec. 2018 In Kolkata, a delta city in the east, where summers are sticky and hot anyway, the monsoon is becoming particularly harsh: The city’s June-September heat index climbed by 0.26 degrees Celsius per decade. Somini Sengupta, The Seattle Times, "In India, summer heat could soon be unbearable — literally," 17 July 2018

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


circa 1929, in the meaning defined above

Communications code word

1952, in the meaning defined above

History and Etymology for delta

Noun and Adjective

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

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Statistics for delta

Last Updated

25 May 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

Comments on delta

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behavior toward others

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