# δ

Character δ GREEK SMALL LETTER DELTA U+03B4 Greek and Coptic

## Translingual

### Symbol

δ

1. (mathematics) A small increment or change in a variable.
$\delta$$x$ is a small change in variable $x$
2. (mathematics, calculus of variations) Denotes a small — rather infinitesimalvariation of the value returned by a functional and/or of the functions on which that functional depends. This symbol can also — along a similar vein — be used to help denote virtual displacement and virtual work.
3. (mathematics) A small number, usually accompanied by ε.
• For any $\epsilon>0$, there is a $\delta$$>0$
4. (mathematics) Kronecker delta or Dirac delta.

## Greek

### Etymology

Derived from its majuscule counterpart Δ, from the Phoenician letter 𐤃, dalet.

### Letter

δ (d) (lowercase, uppercase Δ)

1. Lower case delta (δέλτα), the fourth letter of Greek alphabet. It represented in Ancient Greek a voiced dental plosive: IPA(key): /d/ and in modern Greek a voiced dental fricative: IPA(key): /ð/. It is preceded by γ and followed by ε.