Pi (/ˈpaɪ/; Ancient Greek /piː/ or /peî/, uppercase Π, lowercase π, cursive ϖ; ) is the sixteenth letter of the Greek alphabet, meaning units united, and representing the voiceless bilabial plosive. In the system of Greek numerals it has a value of 80. It was derived from the Phoenician letter Pe. Letters that arose from pi include Latin P, Cyrillic Pe (П, п), Coptic pi (Ⲡ, ⲡ), and Gothic pairthra (𐍀).

Uppercase Pi

The uppercase letter Π is used as a symbol for: In science and engineering: Π (in analogy to the use of the capital Sigma Σ as summation symbol).

Lowercase Pi

The lowercase letter π is used as a symbol for:

History

An early form of pi was, appearing almost like a gamma with a hook.

Variant pi

Variant pi or "pomega" (\varpi,! or ϖ) is a glyph variant of lowercase pi sometimes used in technical contexts. It resembles a lowercase omega with a macron, though historically it is simply a cursive form of pi, with its legs bent inward to meet. It was also used in the minuscule script. It is a symbol for:

Unicode

Lower-case pi was fairly common in 8-bit character encodings, for instance it is at in CP437 and at on Mac OS Roman. The various forms of pi present in Unicode are: These are intended for use as mathematical symbols. Text written in the Greek language (i.e. words, as opposed to mathematics) should not come from any of the tables on this page, but instead should use the normal Greek letters, which have different code numbers and often a different appearance. Using the mathematical symbols to display words (or vice versa) is likely to result in inconsistent spacing and a clumsy, mismatched appearance: