Greek letter (3 letters)

{ Answer }

PHI

{ Related Clues }

___ Beta Kappa
Beta preceder
Campus letter
Fraternity character
Fraternity letter
Homophone for fie
Key letter
Key opener?
Letter on a key
Sorority character
Upsilon follower
Upsilon's follower
Golden ratio symbol
Honor society letter
Honor society opening
Letter on a certain key
Magnetic flux symbol
___ phenomenon (optical illusion)
Symbol of electric flux
Symbol of the golden ratio
Greek symbol for the golden ratio
Letter seen twice in Philadelphia
N.L. East team, on scoreboards
Letter before Beta in a society's name

{ Tags }

21st, beta, character, flux, follower, fraternity, golden, greek, honor, kappa, key, letter, name, opener, phi, ratio, society, sorority, symbol, upsilon, upsilons

{ Notes }

The answer PHI is seen frequently, appearing about once every 160 puzzles.

{ Definition }

PHI as a noun:

1. the 21st letter of the Greek alphabet