phi
UK[faɪ]US[faɪ]
n
The 21st letter of the Greek alphabet (Φ, φ)
Etymology
The word 'phi' is the English name for the 21st letter of the Greek alphabet. It was borrowed directly from the Greek letter's name, φεῖ (pheî), in the late 16th century. The Greek letter itself is believed to have originated from the Phoenician letter qoph. In modern English, 'phi' is primarily used in academic contexts, particularly in mathematics, physics, and engineering, to represent various constants, angles, or phases.
Analysis
This is a simplex word. It is the English name for the Greek letter Φ (φ). The letter's name in Ancient Greek was φεῖ (pheî).
Examples
The symbol for the golden ratio is the Greek letter phi.
The phase angle is commonly denoted by the lowercase phi (φ).
In physics, magnetic flux is represented by the uppercase phi (Φ).