delta

¹

[ del-tuh ]

noun

1. the fourth letter of the Greek alphabet (Δ, δ).
2. the consonant sound represented by this letter.
3. the fourth in a series of items.
4. anything triangular, like the Greek capital delta (Δ).
5. Mathematics. an incremental change in a variable, as Δ or δ.
6. a nearly flat plain of alluvial deposit between diverging branches of the mouth of a river, often, though not necessarily, triangular:

   the Nile delta.

7. Also Delta. a word used in communications to represent the letter D.
8. Delta, Astronomy. a star that is usually the fourth brightest of a constellation:

   The fourth brightest star in the Southern Cross is Delta Crucis.

Delta

²

[ del-tuh ]

noun

, Military.

1. the NATO name for a class of nuclear-powered submarines armed with multiple-warhead ballistic missiles, including those designed to strike military and industrial installations: first produced for the Soviet Navy in the 1970s; in service with the Russian Navy since 1992.

delta

¹

/ dɛlˈteɪɪk; ˈdɛltə /

noun

1. the fourth letter in the Greek alphabet (Δ, δ), a consonant transliterated as d
2. an object resembling a capital delta in shape
3. 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

4. maths a finite increment in a variable

Delta

²

/ ˈdɛltə /

noun

1. a state of Nigeria, on the Niger river delta on the Gulf of Guinea. Capital: Asaba. Pop: 4 098 391 (2006). Area: 17 698 sq km (6833 sq miles)

Delta

³

/ ˈdɛltə /

noun

1. foll by the genitive case of a specified constellation usually the fourth brightest star in a constellation
2. any of a group of US launch vehicles used to put unmanned satellites into orbit
3. communications a code word for the letter d

delta

/ dĕl′tə /

1. A usually triangular mass of sediment, especially silt and sand, deposited at the mouth of a river. Deltas form when a river flows into a body of standing water, such as a sea or lake, and deposits large quantities of sediment. They are usually crossed by numerous streams and channels and have exposed as well as submerged areas.

Derived Forms

• deltaic, adjective

Word History and Origins

Origin of delta¹

First recorded in 1150–1200; Middle English delta, deltha, from Latin delta, from Greek délta; akin to Hebrew dāleth

Word History and Origins

Origin of delta¹

C16: via Latin from Greek, of Semitic origin; compare Hebrew dāleth

Example Sentences

The debate centers on a measure that calls for prioritizing additional flows for endangered delta smelt, a species that has suffered major declines and is thought to be nearing extinction in the wild.

From Los Angeles Times

Ominously, the Paraná delta — the second largest river in South America after the Amazon — caught fire several years ago amid terrible drought.

From Salon

Two meteor showers visible from the Northern Hemisphere, the Southern delta Aquariids and the alpha Capricornids, will peak between Monday and Wednesday.

From Los Angeles Times

And sea level rise is likely to complicate water managers’ efforts to manage salinity levels and meet water quality standards in the delta.

From Los Angeles Times

Leaders of environmental groups said they hope federal protections can help save the fish by placing additional restrictions on the pumping of water from the delta.

From Los Angeles Times

Related Words

• box
• cavity
• door
• entrance
• gate
• rim