Phi (disambiguation)

Phi is the name of:

• The 21th letter of the Greek alphabet.
• The Phi phenomenon.
• In engineering, capital letter Φ is generally used to denote the diameter of a circular section (Φ14 means the diameter of the circle is 14 inches or millimeters, depending on the context).
• The greek letter used to represent the so-called Golden mean
• In spherical coordinates phi is usually used to represent the angle to the z axis