the fourth letter of the Greek alphabet (Δ, δ).
the consonant sound represented by this letter.
the fourth in a series of items.
anything triangular, like the Greek capital delta (Δ).
Mathematics. an incremental change in a variable, as Δ or δ.
a nearly flat plain of alluvial deposit between diverging branches of the mouth of a river, often, though not necessarily, triangular.
the Nile delta.
Also Delta a word used in communications to represent the letter D.
Astronomy. Delta, a star that is usually the fourth brightest of a constellation.
The fourth brightest star in the Southern Cross is Delta Crucis.
(foll by the genitive case of a specified constellation) usually the fourth brightest star in a constellation
any of a group of US launch vehicles used to put unmanned satellites into orbit
communications a code word for the letter d
the fourth letter in the Greek alphabet (Δ, δ), a consonant transliterated as d
an object resembling a capital delta in shape
(capital when part of name) the flat alluvial area at the mouth of some rivers where the mainstream splits up into several distributaries
the Mississippi Delta
maths a finite increment in a variable
First recorded in 1150–1200; Middle English delta, deltha, from Latin delta, from Greek délta; akin to Hebrew dāleth
Named for the fourth letter of the Greek alphabet (shaped like a triangle), a delta is a triangular area where a major river divides into several smaller parts that usually flow into a larger body of water. The first so-called delta was the Nile Delta, named by the Greek historian Herodotus. What makes a delta so special? Alluvial deposits are the rich mineral soil that can be found in the delta. Despite frequent floods, farmers often settle in a delta for this reason. Here's some more fun delta trivia: the deltoid muscles in your shoulders are named after the fourth letter of the Greek alphabet too.
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The project was planned for two areas along the Adriatic coast -- the protected delta area of Vjosa-Narta and the nearby uninhabited island of Sazan, once secret communist military base.
From Barron's • Jun. 4, 2026
A high delta means the convertibles track the stock closely.
From Barron's • Jun. 2, 2026
When traders buy S&P 500 call options, the dealers who sell those calls need to buy S&P 500 futures to remain what’s called delta neutral.
From MarketWatch • Apr. 20, 2026
The study identifies groundwater depletion as the strongest overall factor linked to delta subsidence, although the main cause varies by region.
From Science Daily • Apr. 20, 2026
Yes, everything was once water, but the Earth formed out of the oceans by a natural process—similar, he thought, to the silting he had observed at the delta of the Nile.
From "Cosmos" by Carl Sagan
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
