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. Astronomy.,  Delta, 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

/ 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

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

/ 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

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.

Other Word 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

Ms. Low rehashes that old story, but concedes the delta is at least partially a product of the fact that “many women want to spend time at home with their children.”

Read more on The Wall Street Journal

The country is essentially a large delta crossed by three major rivers, the Rhine, Schelde, and Maas, that flow into the unpredictable North Sea.

Read more on Barron's

Over time, sediment carried by rivers built deltas at the head of the Gulf, cutting off tidal access to inland areas.

Read more on Science Daily

Many of its largest cities -- including Shanghai, Shenzhen and Hong Kong -- sit in delta regions made of soft, water-saturated sediment that naturally sinks over time.

Read more on Science Daily

At Martín García Island, Argentina, a series of crags amid the Río de la Plata delta, she tries to make sense of crooked crosses cast from a single mold.

Read more on Los Angeles Times

Related Words

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