. "Phi (uppercase \u03A6, lowercase File:Greek Phi normal.svg or File:Greek phi Didot.svg; Ancient Greek: \u03D5\u03B5\u1FD6, phe\u00EE, [p\u02B0\u00E9\u035Ce]; modern Greek: \u03C6\u03B9, fi, [fi]; English: /fa\u026A/) is the 21st letter of the Greek alphabet. In Ancient Greek, it represented an aspirated voiceless bilabial plosive ([p\u02B0]), which was the origin of its usual romanization as \"ph\". In modern Greek, it represents a voiceless labiodental fricative ([f]) and is correspondingly romanized as \"f\"."@en . .