Delta (letter)
| Greek letters | |
| Α α Alpha | Β β Beta |
| Γ γ Gamma | Δ δ Delta |
| Ε ε Epsilon | Ϝ ϝ Digamma |
| Ζ ζ Zeta | Η η Eta |
| Θ θ Theta | Ι ι Iota |
| Κ κ Kappa | Λ λ Lambda |
| Μ μ Mu | Ν ν Nu |
| Ξ ξ Xi | Ο ο Omicron |
| Π π Pi | Ϻ ϻ San |
| Ϙ ϙ Qoppa | Ρ ρ Rho |
| Σ σ Sigma | Τ τ Tau |
| Υ υ Upsilon | Φ φ Phi |
| Χ χ Chi | Ψ ψ Psi |
| Ω ω Omega | Ϡ ϡ Sampi |
| Greek alphabet | |
Delta (upper case Δ, lower case δ) is the 4th letter of the Greek alphabet. In the system of Greek numerals it has a value of 4.
A river delta is named after the letter delta because it has roughly the triangular shape of the upper-case delta.
The upper-case letter Δ is used as the symbol for:
- A macroscopic change in the value of a variable in mathematics or science.
- Any of the delta particles in particle physics.
- A microscopic change in the value of a variable in mathematics or science.
- The Kronecker delta in mathematics.
- The Dirac delta function in mathematics.
- A mark for deletion in proofreading. The usage is said to date back to classical times.