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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Delta Air Lines was up 0.4% ahead of the open, while United Airlines was down just 0.5% after initially falling close to 3%.
From Barron's • Jun. 8, 2026
Non-tech companies took around half of the top spots in talent readiness, including Delta Air Lines at No. 1.
From The Wall Street Journal • Jun. 8, 2026
Rather than carrying the capital costs of building and deploying projects itself, it collects royalties from partners including Delta Electronics, one of Taiwan’s largest manufacturers, and Doosan, the Korean industrial giant.
From Barron's • Jun. 5, 2026
Across Nigeria's oil-rich southern Niger Delta, decades of oil spills have left a landscape deeply scarred, with wetlands increasingly coated in crude and contaminated sediment.
From BBC • Jun. 3, 2026
The second woman to break the sound barrier was one of Cochran's WASPs, Jean Hixson, who flew a Delta Dagger military jet in 1958, which was against regulations.
From "Women in Space" by Karen Bush Gibson
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.
