Delta (letter)
Greek alphabet History In other languages Scientific symbols Αα Alpha Νν Nu Ββ Beta Ξξ Xi Γγ Gamma Οο Omicron Δδ Delta Ππ Pi Εε Epsilon Ρρ Rho Ζζ Zeta Σσς Sigma Ηη Eta Ττ Tau Θθ Theta Υυ Upsilon Ιι Iota Φφ Phi Κκ Kappa Χχ Chi Λλ Lambda Ψψ Psi Μμ Mu Ωω Omega Archaic local variants  ·  ·  ·  ·  · Ligatures (ϛ, ȣ, ϗ) · Diacritics Numerals: (6) · (90) · (900) Bactrian  · Coptic  · Albanian Book  · Category · Commons

Delta (uppercase Δ, lowercase δ; δέλτα; Modern Greek [ˈðelta] dhélta) is the fourth letter of the Greek alphabet. In the system of Greek numerals it has a value of 4. It was derived from the Phoenician letter Dalet. Letters that come from delta include Latin D and Cyrillic Д.

A river delta (originally, the Nile River delta) is so named because its shape approximates the upper-case letter delta (the shape is a triangle).

The alphabet on a black figure vessel, with a D-shaped delta.

## Pronunciation

In Ancient Greek, it represented a voiced dental plosive /d/. In Modern Greek, it represents a voiced dental fricative /ð/, like the "th" in "that" or "this". It is romanized as d or dh.

## Mathematics and the Sciences

### Upper case

The upper-case letter Δ can be used to denote

• Change of any variable quantity, in mathematics and the sciences; for example, in
${y_2-y_1\over x_2-x_1} = {\Delta y \over \Delta x}$, the average change of y per unit x, i.e. the change of y over the change of x
$\Delta f = \sum_{i=1}^n {\frac{\partial^2 f}{\partial x_i^2}}$
$\Delta = b^2 - 4ac\,\!$
• A macroscopic change in the value of a variable in mathematics or science
• Uncertainty in a physical variable as seen in for instance the uncertainty principle
• An interval of possible values for a given quantity for instance across a sample[citation needed]
• Any of the delta particles in particle physics
• The determinant of the matrix of coefficients of a set of linear equations (see Cramer's Rule)
• That an associated locant number represents the location of a covalent bond in an organic compound, the position of which is variant between isomeric forms
• In chemistry, it is often used to represent the addition of heat in a reaction.
• In legal shorthand, it represents a defendant
• In the financial markets, it is one of the Greeks that describes the rate of change of an option price for a given change in the underlying benchmark
• It is the symbol of the Greek inventor and architect Daedalus
• In genetics, it can stand for a gene deletion, e.g. the CCR5-Δ32 a deletion of the CCR5 at the 32nd base pair segment
• The American Dental Association cites it (together with omicron for "odont") as the symbol of dentistry.[2]

### Lower case

The lower-case letter δ can be used to denote

## References

Wikimedia Foundation. 2010.

### Look at other dictionaries:

• Delta — commonly refers to: Delta (letter), Δ or δ in the Greek alphabet, also used as a mathematical symbol River delta, a landform at the mouth of a river Delta Air Lines, a major U.S. airline Delta may also refer to: Contents 1 Places …   Wikipedia

• Delta Lambda Phi — ΔΛΦ Founded October 15, 1986 (1986 10 15) (25 years ago) Washington, D.C. Type Social Scope National …   Wikipedia

• Delta Chi — ΔΧ Founded October 13, 1890 (1890 10 13) (121 years ago) Cornell University …   Wikipedia

• Delta Upsilon — ΔΥ Founded November 4, 1834 (1834 11 04) …   Wikipedia

• Delta (rocket family) — Delta Family The Delta rocket family. Role Expendable launch system with various applications …   Wikipedia

• Delta Sigma Theta — ΔΣΘ Founded January 13, 1913 (1913 01 13) …   Wikipedia

• Delta Omicron — ΔΟ Founded September 6, 1909 Cincinnati Conservatory of Music, Cincinnati, Ohio Type Professional …   Wikipedia

• Delta — Del ta, n.; pl. {Deltas}. [Gr. de lta, the name of the fourth letter of the Greek alphabet (the capital form of which is [Delta], Eng. D), from the Ph[oe]nician name of the corresponding letter. The Greeks called the alluvial deposit at the mouth …   The Collaborative International Dictionary of English

• Delta State University — seal Established 1924 Type Public, Co ed P …   Wikipedia

• Delta Sigma Pi — ΔΣΠ Founded November 7, 1907 (1907 11 07) (104 years ago) New York University …   Wikipedia