Pi (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 | |
Pi (upper case Π, lower case π) is the 16th letter of the Greek alphabet. In the system of Greek numerals it has a value of 80. In words it is pronounced /p/.
The upper-case letter Π is used as a symbol for:
- The product operator in mathematics (similar to a series).
- In textual criticism, Codex Petropolitanus, a 9th century, uncial codex of the Gospels, now located in St. Petersburg, Russia.
- The mathematical constant &pi 3.14159, being the ratio of a circle's circumference to its diameter.
- The prime counting function in mathematics.
- The pi mesons in particle physics.
- Profit in economics.