Yes, phi is a Scrabble word!
...and is worth 8 points in Scrabble, and 8 points in Words with Friends
phi
Noun
1. The 21st letter of the Greek alphabet
What Scrabble words can I make with the letters in phi?
3 Letter Words
2 Letter Words
Noun
1. The 21st letter of the Greek alphabet
3 Letter Words
2 Letter Words