delta1
/ˈdɛltə
/noun
1The fourth letter of the Greek alphabet (Δ, δ), transliterated as ‘d’.Other symbols use in chemistry include the Greek letter delta to denote a change in energy levels and an arrow to indicate the direction a reaction proceeds in....
- Casey guessed the next would be delta: phonetic alphabet
- Apparently they don't teach you anything useful, just epsilons and deltas.
1.1British A fourth-class mark given for an essay, examination paper, or other piece of work.
1.2 [as modifier] The fourth in a series of items, categories, etc. delta hepatitis...
- The study reports the influence of delta infection on the severity of hepatitis B.
- To me it looked like the alpha males on the rampage, and alpha males are always scary to all the gamma and delta males.
- Our results suggest that delta infection may not be very common in Indian patients with HBV-related liver diseases.
1.3 (Delta) [followed by Latin genitive] Astronomy The fourth (usually fourth-brightest) star in a constellation: Delta Cephei...
- Other bright stars in Canis Major are Adhara (Epsilon Canis Majoris), Mirzam (Beta Canis Majoris), and Wezen (Delta Canis Majoris).
- As a connecting star to Pegasus, it is also known as Delta Pegasi, though this name is rarely used.
2A code word representing the letter D, used in radio communication.Pilot: Regina Tower, (this is) Cessna foxtrot bravo charlie delta (over).
3 (also delta connection) A triangular arrangement of electrical three-phase windings.After the start, the circuit is switched to delta connection and the motor receives the nominal voltage....
- The voltage and current rules for a delta connection must be used when determining line and phase values of voltage current.
- The respective delta connections of each main and additional windings are three delta points,, and of the main winding which are perfectly symmetrical and equidistant from each other.
symbol
1 (δ) Mathematics Variation of a variable or function.
2 (Δ) Mathematics A finite increment.
3 (δ) Astronomy Declination.
Origin
Greek, from Phoenician daleth.
The triangular area of sediment at the mouth of some rivers takes the name delta from its shape, which is like that of the triangular fourth letter of the Greek alphabet, called delta. The original delta was at the mouth of the River Nile, which was called the Delta from the mid 16th century. The shape of the Greek letter also gave its name to the delta wing, a triangular swept-back wing fitted on some jet aircraft, immediately after the Second World War.
Rhymes
delta2
/ˈdɛltə/noun
A triangular tract of sediment deposited at the mouth of a river, typically where it diverges into several outlets: the Nile delta [as modifier]: a huge delta system developed...
- It and many other old zircons come from metamorphosed sediments deposited in river deltas some 3 billion years ago in what is now southwestern Australia.
- Discriminating between deposits of tidally influenced deltas and tide-dominated coastal mud flats in the rock record is often difficult.
- Innumerable lagoons, lakes, canals, estuaries and the deltas of 44 rivers make up the 900 km of backwater network of the State.
Derivatives
deltaic
/ adjective ...- Flows may have been storm-triggered or represent hyperpycnal underflows sourced from deltaic distributary channels, indicating the proximity of the coastline.
- Unlike the deltaic, lowland assemblages of the southwestern United States, the Bromacker assemblage contains neither fish nor obligate aquatic tetrapod remains.
- Avery Island is actually a small hill, created in the deltaic wetlands by the upwelling of ancient salt deposits that exist beneath the Mississippi Delta.
Origin
Mid 16th century: originally specifically as the Delta (of the River Nile), from the shape of the Greek letter (see delta1).