What is the Greek letter for 'Phi'?

The Greek letter for 'Phi' is represented by the symbol Φ. In the Greek alphabet, Phi is the 21st letter and is commonly associated with various fields, including mathematics, physics, and engineering. The uppercase form is Φ, while the lowercase is φ.

The other options represent different Greek letters: Ψ corresponds to 'Psi', Ω corresponds to 'Omega', and Σ corresponds to 'Sigma'. Each of these letters has its own distinct pronunciation and symbolic meanings in various contexts, but in this case, Φ is definitively the symbol for Phi.